(Circulation. 1997;96:2675-2682.)
© 1997 American Heart Association, Inc.
Articles |
Inotropic Effects of Glyceryl Trinitrate and Spontaneous NO Donors in the Dog Heart
From the Physiologisches Institut I (B.P., D.E., V.T.), the Institut für Pharmakologie (G.K., K.K., E.N.), and the Institut für Klinische Anaesthesiologie (W.S.), Heinrich-Heine-Universität, Düsseldorf.
Correspondence to Prof Dr Volker Thämer, Physiologisches Institut I, Abteilung für Herz- und Kreislaufphysiologie, Heinrich-Heine-Universität Düsseldorf, Postfach 10 10 07, D-40001 Düsseldorf, Germany. E-mail benedikt{at}herzkreis.uni-duesseldorf.de
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Abstract |
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Background In vitro, NO has a biphasic effect on myocardial inotropy. To determine the inotropic effect of NO in vivo, we investigated the activity of glyceryl trinitrate (GTN) and the NO donors S-nitroso-N-acetyl-D,L-penicillamine (SNAP) and sodium-(2)-1-(N,N-diethyl-amino)-diazen-1-ium-1,2-diolat (DEA/NO) in dogs.
Methods and Results Eight anesthetized open-chest dogs were instrumented for measurement of left ventricular and aortic pressures (tip manometers) and coronary flow (ultrasonic flow probes). Regional myocardial function was assessed by sonomicrometry as systolic wall thickening (sWT), mean systolic thickening velocity (Vs), and regional myocardial stroke work index (RSW). GTN, SNAP, and DEA/NO were infused into the left anterior descending coronary artery (LAD) to achieve defined coronary plasma concentrations of GTN, SNAP (both 10 to 100 µmol/L), and DEA/NO (2 to 20 µmol/L). All drugs increased LAD flow and myocardial contractile function in the LAD-dependent myocardium within the first 120 seconds. The greatest inotropic effect was noted after infusion of DEA/NO (20 µmol/L), which increased sWT by 9.7±3.1% from 28.5±2.2%, Vs by 10.3±3.4% from 9.1±1.1 mm/s, and RSW by 7.1±2.1% from 200.0±22.1 mm Hgxmm (P<.05). At the same time, systemic hemodynamics remained unchanged. Prevention of the flow response to GTN by external narrowing of the LAD did not influence the inotropic effect of GTN.
Conclusions Organic nitrates and NO donors evoke a small but constant positive inotropic effect in vivo that is not caused by coronary vasodilation.
Key Words: endothelium-derived factors • myocardial contraction • contractility • nitroglycerin
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Introduction |
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Organic nitrates and spontaneous NO donors release NO, which also accounts for the biological activity of vascular endothelium-derived relaxing factor.1 NO can potentially influence cardiac function indirectly by altering peripheral and vascular tone and thus cardiac loading conditions and coronary perfusion, respectively. NO has been shown to modulate myocardial contractile function directly. Early investigations demonstrated that GTN exerts positive inotropic actions on ventricular myocardium.2 3 4 Positive inotropic effects have also been demonstrated for different NO-releasing nitrovasodilators.5 6 In the isolated Langendorff-perfused heart, both GTN and SNAP dose-dependently increased dP/dtmax, dP/dtmin, and LVP.7 Other studies suggested a direct inotropic response depending on intracellular levels of cGMP.8 9 10 Small increases in cGMP improved contractile response, whereas a large increase in cGMP reduced contractile activity of isolated rat cardiomyocytes.8 A similar biphasic effect was observed in isolated cat papillary muscles.10 In contrast, isolated negative inotropic effects of NO have been observed in various in vitro models.9 11 12 13 14
Inotropic effects of nitrovasodilators were rarely studied in vivo.15 16 17 18 It remains uncertain whether NO is able to improve myocardial contractile function in vivo because changes in systemic hemodynamics may cover local inotropic effects. The aim of the present study was to investigate the local inotropic response of NO-releasing drugs before the onset of changes in global hemodynamics. Therefore, in open-chest dogs, GTN, SNAP, and DEA/NO were infused into a coronary side branch of the LAD, and changes in regional myocardial function were determined by sonomicrometry. This method allows us to assess direct inotropic effects and to distinguish them from global systemic vascular effects. Changes in regional myocardial function caused by drug-induced alterations of coronary flow19 were excluded by prevention of the flow response to GTN infusion by external LAD tightening.
Our study demonstrates that NO donors elicit a small, direct, positive inotropic effect independent of the concomitant increase of coronary flow.
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Methods |
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Experimental procedures complied with the "Guiding Principles in the Use and Care of Animals" approved by the Council of the American Physiological Society and with local and state regulations. The program was approved by the bioethical committee of the District of Düsseldorf.
Animal Preparation
Eight beagle dogs of either sex (16 to 21 kg) were
anesthetized with intravenous sodium thiamylal
(17.5 mg · kg-1) followed by piritramid
(1 mg · kg-1 ) and midazolam (1 mg
· kg-1). After endotracheal intubation,
ventilation was controlled to maintain an arterial
PCO2 of 
35 mm Hg (Sulla 19, Pulmomat
19 K.1 ventilator, Dräger-Werke AG). Anesthesia was
maintained with continuous piritramid (6 mg ·
h-1) and midazolam (6 mg ·
h-1) infusion. Additional bolus doses were
given as needed during the surgical preparation, and 70% nitrous oxide
was added but was discontinued at least 20 minutes before the
experiment. The adequacy of this anesthesia regimen was
demonstrated by lack of muscle movement and hemodynamic
responses during surgical preparation. Neuromuscular block during
thoracotomy was then achieved by injection of pancuronium bromide (0.1
mg · kg-1). Loss of fluid was
compensated for by the infusion of normal saline to maintain the
hematocrit within normal limits. Body temperature was maintained within
physiological limits by a heating pad. LVP and AOP
were monitored with two catheter-tip manometers (Micro-Tip Pressure
Transducer, PC-350 A, Millar Instruments) introduced from the left
atrium and the right femoral artery, respectively. After left
thoracotomy and pericardiotomy, the LAD and the LCx were dissected free
and metered flow probes (Transonic Systems Inc) were fitted around the
vessels to measure blood flow. The first side branch of the LAD distal
to the flow probe was cannulated with a small polyethylene catheter
(0.8-mm OD), and the tip of the catheter was advanced at the origin of
the side branch of the LAD to allow intracoronary infusion into
the LAD-perfused myocardium. A snare occluder was placed
around the LAD for later external tightening of the LAD to prevent
drug-induced flow response. Two pairs of ultrasonic crystals (Triton
Technology Inc) were implanted in both the left anteroapical and
posterobasal wall to assess regional myocardial function. One crystal
of each pair was placed in the subendocardium, and the other was fixed
epicardially. The ultrasonic signal was monitored on an oscilloscope
(Tektronix 453, Tektronix Inc) to verify correct crystal alignment. A
snare was placed around the inferior vena cava to allow
reduction of LV preload by tightening of the snare. The hearts were
paced via the left atrium at 100 to 120 bpm, depending on the
individual spontaneous sinus rhythm frequency (for preparation, see Fig 1
).
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Substances and Solutions
SNAP was synthesized according to the method of Field and
colleagues20 as described previously.8 The
NO-liberating property of synthesized SNAP, determined by the
oxyhemoglobin assay, yielded an NO formation rate of 1.28±0.01
µmol · L-1 ·
min-1 (n=3) with 1 mmol/L SNAP in
the reaction tube. GTN (4.404 mmol/L in 247
mmol/L D(+)-glucose monohydrate, used directly as
stock solution) was purchased from G. Pohl-Boskamp GmbH & Co. DEA/NO
was a gift of Dr L. Keefer (National Cancer Institute, Frederick, Md),
and all other chemicals (analytical grade) were obtained from Merck.
Stock solutions of DEA/NO (10 mmol/L) in 10
mmol/L NaOH, SNAP (10 mmol/L) in dimethyl sulfoxide
(5%), and sodium nitroprusside (0.5 mmol/L) were prepared
daily, diluted with NaCl (154 mmol/L), protected from
daylight, and kept on ice until use. All concentrations indicated in
the text, figures, and tables are expressed as final plasma
concentrations.
Experimental Protocol
After the surgical preparation, we started the experimental
protocol once all hemodynamic variables had
attained steady-state values. In five dogs, vehicle was infused into
the coronary side branch (Precidor HT infusion pump, Inøfors
AG) in the highest concentration later used to exclude possible effects
on global hemodynamics and regional myocardial function
(glucose changed RSW, Vs, and sWT by 1.4±1.6%,
-1.2±0.7%, and 0.7±1.9% from control, respectively; dimethyl
sulfoxide, by -0.5±0.9%, 0.8±2.3%, and 1.4±1.1% from control;
and NaOH, by -1.4±0.5%, -2.0±1.7, and -2.7±2.5% from control,
n=5). Measurement periods were therefore compared with control periods
without infusion of vehicle. Stock solutions were infused via the
cannulated side branch into the LAD for 180 seconds, with infusion rate
adjustment to LAD flow to achieve coronary plasma
concentrations of 10, 50, and 100 µmol/L GTN and SNAP and
2, 10, and 20 µmol/L DEA/NO. Plasma concentrations were
calculated from coronary blood flow corrected for hematocrit.
The sequence of drug infusions and the sequence of concentrations
applied were randomized. Control measurements were performed
immediately before each drug application. The drugs needed 60 seconds
to pass the catheter. Between injections, the remaining capacity of the
catheter was withdrawn, and sufficient washout time (15 minutes) was
allowed to ensure that the drug was eliminated before the next infusion
was carried out. Additional measurements were performed during
norepinephrine injection (0.5 µg) into the
coronary side branch to investigate the contractile response of
the LAD-perfused area to catecholamine stimulation in three
animals. Intracoronary doses between 0.1 and 0.5 µg
norepinephrine have been found in previous studies to
affect only the local myocardium supplied by the respective
coronary artery.21 22 Intracoronary
norepinephrine produced typical inotropic effects in the
myocardium,21 as demonstrated by an increase
in dP/dtmax from 1851±278 to 2377±321 mm Hg and an
improvement of regional myocardial function: RSW increased from
251.6±45.2 to 337.5±72.7 mm Hgxmm, Vs from
11.7±0.7 to 26.2±2.0 mm/s, and sWT from 35.6±0.9% to
57.5±2.3%, respectively. To determine the influence of preload
reduction, myocardial function was assessed during external tightening
of the inferior vena cava. Measurements were also performed
while the LAD flow response to infusion of GTN (100
µmol/L) was prevented by tightening of the vessel to
investigate regional myocardial function independent of
coronary flow changes.
Because of the known effects of NO donors on methemoglobin formation,23 24 25 methemoglobin was measured in arterial blood samples every hour. Methemoglobin content at the beginning of three experiments was 0.8%, 1.1%, and 1.2% of total hemoglobin, compared with 0.6%, 1.3%, and 1.3% of total hemoglobin at the end of the experiments, respectively; hence, there was no relevant increase in systemic methemoglobin content during the experiments.
In the end, the hearts were arrested in diastole by cardioplegic perfusion through the aortic root, and the LAD was cannulated at the site of the flow probe and perfused with 0.2% Evans blue dye added to normal saline while the rest of the myocardium was perfused through the aortic root with 1% dextran in normal saline. The heart was excised, and the mass of the LAD-perfused area was determined.
Data Analysis and Statistics
LVP and its first derivative dP/dt, blood flow through the LAD
and the LCx, and anteroapical and posterobasal myocardial wall
thicknesses were continuously recorded with an ink recorder
(Recorder 2800, Gould Inc) and stored on videotape (SL-C 30 PS,
Sony) with pulse code modulation (VPMD 8-12, Fa. Heim) for later
playback and analysis. The data were digitized with an
analog-to-digital converter (Data Translation) at a sampling rate of
500 Hz and later processed on a personal computer.
Global LV function was measured in terms of LVSP and the maximum rate of pressure increase (dP/dtmax) and decrease (dP/dtmin). Global LV end systole was defined as peak negative dP/dt26 27 and LV end diastole as the beginning of the sharp upslope of the LV dP/dt tracing. Systolic time was defined as the time interval from end diastole to end systole.
Regional myocardial systolic function was assessed separately in two regions: in the posterobasal wall (LCx-perfused area) and in the anteroapical wall (LAD-perfused area). Regional end systole was determined as the point of maximal wall thickness within 20 ms before dP/dtmin.28 Regional systolic contractile function was evaluated as sWT (systolic wall excursion as percentage of end-diastolic wall thickness) and as Vs (systolic wall excursion divided by systolic time). RSW was measured to determine changes of local myocardial work. To assess RSW, pressure–wall thickness loops during drug infusion were obtained. The area of each loop was calculated by electronic integration and corresponds to the RSW. The mean values of 8 to 12 consecutive beats during expiration were obtained for measurement of all variables to compensate for respiratory variations. Measurements were performed 120 seconds after the start of drug infusion. At this time, drug infusion led to an increased LAD flow and changes in inotropic response of the anteroapical wall but did not change either flow values and inotropic response in the posterobasal wall or systemic hemodynamics.
All values are expressed as mean±SEM. Each control was compared with the respective intervention (drug administration) by Student's t test for paired observations followed by a Bonferroni correction for each drug group. Comparison of LAD flow changes and comparison of inotropic effects between the different concentrations as well as between the different NO donors were done by ANOVA. A probability value of <.05 was considered significant.
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Results |
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A total of eight dogs were studied. In one dog, electronic data of one recording channel were lost in one intervention (SNAP 10 µmol/L), and it was excluded from the analysis in the respective measurement period. In all other dogs, complete data sets were obtained. The average weight of the LAD perfusion territory was 27.4±2.3 g.
Effects of Intracoronary Administration of GTN and NO
Donors
Effects on global hemodynamics. Fig 2 shows a representative
original registration of the hemodynamic variables
during intracoronary infusion of 20 µmol/L
DEA/NO. The global hemodynamic data of the control and
measurement periods are summarized in Table 1. During the measurement period,
increases of the LAD flow and changes of the wall thickness in the
anteroapical wall could be observed. None of the substances showed
systemic hemodynamic effects during the measurement
periods (unchanged LVSP, LVEDP, and AOP). In addition, LCx flow also
remained unchanged. There was no effect on global
ventricular function (LVSP, dP/dtmax, and
dP/dtmin). At any concentration, GTN, SNAP, and DEA/NO
induced a significant increase of LAD flow after 120 seconds of drug
application (Table 1), ranging from an increase of 24.6±9.0% from
93.6±14.5 mL · 100 g-1 ·
min-1 (SNAP, 10 µmol/L) to the
maximum increase of 77.0±14.9% from 82.4±9.4 mL · 100
g-1 · min-1,
achieved by infusion of DEA/NO (10 µmol/L). No
dose-dependent effect on coronary flow was observed, suggesting
that all NO donors were maximally effective at the lowest concentration
used.
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Effects on regional myocardial function. The NO donors
improved the indices of regional myocardial function in the
anteroapical wall during the measurement period (Table 2, Figs 3 and 4). The
overall regional positive inotropic effect was small in comparison with
that of intracoronary norepinephrine (0.5 µg)
injection; in no case, however, was there a negative inotropic response
of the LAD-perfused myocardium. For example, DEA/NO at a
concentration of 20 µmol/L increased RSW by 7.1±2.1%
from 200.1±22.1 mm Hgxmm, sWT by 9.7±3.1% from 28.5±2.2%,
and Vs by 10.3±3.4% from 9.1±1.1 mm/s. No
dose-dependent effect was observed in each drug group. SNAP and DEA/NO
tended to improve regional myocardial function to a greater extent than
did GTN (Fig 4); however, these differences were not significant. At
the same time, the indices of regional myocardial function in the
posterobasal wall (LCx-perfused area) did not change (data not shown),
indicating specific drug effects in the LAD-perfused
myocardium during the measurement periods.
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Effects of GTN on regional myocardial function in presence
of artificially maintained coronary flow. Prevention of
the LAD flow response during infusion of GTN by external narrowing of
the vessel with a snare occluder did not blunt the inotropic effect of
GTN (Fig 5), indicating that the improved
regional myocardial function is not due to the increased
coronary flow. In fact, LAD flow decreased by 13.6±5.8% from
83.0±11.4 mL · 100 g-1 ·
min-1 (P=.10), while sWT in the
anteroapical wall concomitantly increased by 3.7±1.5% from
29.2±1.4 mm (P<.05), Vs by
6.3±1.7% from 5.2±1.9 mm/s (P<.05), and RSW by
4.6±2.0% from 205.6±15.1 mm Hgxmm (P=.06,
n=6).
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Preload Reduction
The snare around the inferior vena cava was tightened
to determine the effects of preload reduction on myocardial function.
LVSP was reduced from 107.1±7.8 to 85.9±3.9 mm Hg
(P<.05) and LVEDP from 9.5±0.7 to 8.0±0.8 mm Hg
(P<.05). Indices of regional myocardial function decreased
in both wall regions, indicating reduced myocardial contractile
function due to preload reduction (Table 3).
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Discussion |
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We investigated the inotropic effects of organic nitrates and spontaneous NO donors in the dog heart in vivo. The main finding is that the concentrations of the NO donors GTN, SNAP, and DEA/NO we used evoked a small but constant increase in regional myocardial contractile function. These effects were independent of the coronary flow response and provide evidence that NO has direct positive inotropic effects in the dog heart in vivo.
The main difficulty in determination of inotropic effects of NO in vivo
is the numerous systemic hemodynamic side effects of
higher NO levels, ie, a reduction of preload and
afterload.15 29 Therefore, we investigated the regional
inotropic effects of high concentrations of NO donors at a time when
systemic hemodynamics were not yet altered. The changes
in regional myocardial function observed in the experiments are most
likely mediated by NO, because NO is the active agent of all drugs
used. NO donors such as SNAP and DEA/NO spontaneously generate NO
without additional cofactors.30 31 Organic nitrates such
as GTN are bioactivated to NO not only in
vitro32 33 but also in vivo34 by the support
of enzymatic catalysis. Release of NO from GTN also occurs in isolated
cardiomyocytes.8 NO produces its biological
effects predominantly by increasing the production of cGMP in
smooth muscle cells of the vascular wall as well as in isolated
cardiomyocytes.8 35 The increase of cGMP
levels in rat ventricular myocytes incubated with GTN has
been shown to be time dependent, with a maximal increase after 60
seconds of incubation. A similar effect was produced by the NO donor
SNAP. In the present study, we determined myocardial function 60
seconds after the first local effects could be observed (120 seconds
after the start of drug infusion), proposing that at this time regional
inotropic effects should be evident, while systemic effects are still
absent. Indeed, the results show an increased LAD flow, while systemic
hemodynamics (AOP, LVEDP, and LCx flow) remained
unchanged (Fig 2
, Table 1). Furthermore, both
norepinephrine and the nitrovasodilators improved regional
myocardial function only in the LAD-perfused area, indicating
limitation of inotropic effects to the site of drug infusion.
GTN, SNAP, and DEA/NO infused into the coronary side branch
significantly increased LAD flow in each concentration used. An
increase of regional myocardial function as a result of an increase of
coronary blood flow and perfusion pressure has been
discussed.16 19 36 37 A vasodilatation of the LAD should
lead to an increased wall thickness due to higher myocardial blood
volume, resulting in decreased sWT, if myocardial function remained
unchanged. However, sWT was increased in the LAD-dependent
myocardium (Table 2), indicating an improved regional
myocardial function. In addition, preventing the LAD flow response to
infusion of GTN (100 µmol/L) did not influence the
positive inotropic effect (Fig 5). Thus, it is unlikely that the
observed changes in regional myocardial function are caused by an
increased coronary flow.
Positive inotropic effects of organic nitrates and NO have been demonstrated in vitro.2 3 4 5 6 A recent study revealed a concentration-dependent biphasic contractile response of cGMP levels in isolated cardiac tissue preparations.8 A small increase in basal cGMP, the second messenger mediating the effects of NO, was associated with an improved contractile response of isolated cardiomyocytes and isolated rat hearts,38 whereas marked elevations of cGMP decreased contractile activity. This biphasic contractile response to NO and cGMP was also found in cat papillary muscle.10
Even high concentrations of GTN (100 µmol/L) only moderately elevated basal cGMP levels in isolated rat cardiomyocytes.8 By contrast, strong increases in cGMP were obtained after subjection of cardiomyocytes to concentrations of the spontaneous NO donors SNAP and DEA/NO as high as 100 µmol/L. At the plasma concentrations used in the present study, it is unlikely that such high intracellular concentrations were achieved. Accordingly, we did not observe a negative inotropic effect that was previously observed in vitro.11 12 13 14 In humans, the NO donor sodium nitroprusside has no negative inotropic effects but improves myocardial relaxation.39 It has been shown that endogenous NO production in the normal heart in vivo might elicit a negative inotropic effect.17 Conversely, results obtained after intravenous infusion of the NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) showed a decrease in stroke volume that was not caused by reflex mechanisms following increases in blood pressure and systemic vascular resistance but rather indicated a positive inotropic action of endogenous NO.40 Similar results were obtained in the rat in vivo.41 By contrast, conditions that increase endogenous NO production, such as cytokine-induced expression of inducible NO synthase, are associated with a diminished contractile response in isolated cardiomyocytes and multicellular myocardial preparations.12 13 14
Hemodynamic side effects such as vasodilation and preload reduction do not play a role in in vitro investigations. In our study, only an early evaluation of the regional myocardial function was possible, because 180 seconds after the drug infusion was begun, systemic effects were observed. It may be possible that later changes in inotropic effects were covered by the systemic vasodilation, because preload reduction decreased regional myocardial function, as was shown by the vena cava occlusion maneuver. In contrast to the in vitro studies, we infused the drugs into blood-perfused myocardium. The well-known rapid inactivation of NO by hemoglobin23 24 most likely scavenged a considerable amount of NO released by the NO donors. Therefore, the final concentration of NO occurring at the level of the cardiomyocytes was probably lower than the initially infused concentration of the drugs. Our results are consistent with previous in vitro findings showing that a positive inotropic effect of NO at concentrations as low as those probably occurred in cardiomyocytes in this study. Thus, it is not surprising that we did not observe a negative inotropic effect.
Only a few studies investigated the inotropic effects of
nitrovasodilators in vivo.15 16 17 18 39 42 In support of our
results, Raff et al15 demonstrated that both
intravenous and intracoronary infusion of GTN cause
an increase in global LV function in anesthetized dogs,
provided that AOP and LVEDP are kept constant. They observed an
increased dP/dtmax that could not be explained exclusively
by changes in heart rate. A recently published study in short-term
instrumented anesthetized cats showed that administration of a
low-dose infusion of a cGMP analogue induced a significant positive
inotropic effect in the absence of changes in loading
conditions,42 whereas bolus injections of the same cGMP
analogue caused an immediate fall in LVP followed by a decrease in LV
contractile function. These observations indicate that cGMP exerts
direct myocardial positive inotropic effects in the absence of
peripheral vasodilation in vivo. In contrast to these
studies, Crystal and Gurevicius16 failed to show a direct
influence of different nitrovasodilators on myocardial
contractility. In their study, however, GTN
concentrations were chosen to offer the maximum increase in
coronary blood flow without influencing the systemic
hemodynamics. Infusion rate was not adjusted to
coronary flow, resulting in a dilution of GTN. Therefore, the
effective concentration of NO at the cardiomyocyte might
have been too low to demonstrate direct myocardial influences. We
infused GTN to achieve plasma concentrations fourfold to eightfold
higher (50 and 100 µmol/L) than the concentration
used by Crystal and Gurevicius and observed improved myocardial
contractile function (Table 2).
Different indices of regional myocardial function were determined in
our study: sWT reflects the regional contractile function during the
global LV systole; Vs also depends on systolic
time. Mean velocity was determined, because peak velocity is
susceptible to variations in the regional myocardial
contraction.43 Both variables were calculated from the
wall thickness at end diastole and the maximum wall
thickness within 20 ms before end systole28 and have been
used previously to investigate inotropic drug
effects.21 44 The index of myocardial work (RSW) was
calculated from the wall thickness and LVP. The ability of changes in
these variables to reflect changes in regional contractile function
is limited by variations in heart rate and in the loading conditions of
the heart.45 Therefore, heart rate was kept constant
during the experiments (left atrial pacing). During measurement
periods, the indices of afterload (mean AOP) and preload (LVEDP)
remained unchanged (Table 1), suggesting that this methodological
limitation does not affect the results. Although the measurements were
made before the appearance of systemic hemodynamic
effects, the known influence of NO donors on preload should be
considered.29 However, preload reduction by narrowing the
inferior vena cava resulted in a reduced regional
contractile function (Table 3). Therefore, it is unlikely that the
improved myocardial function after intracoronary infusion of NO
donors is due to changes in preload.
Nitrate tolerance has been reported during infusion of organic nitrates46 47 and might have occurred during the repetitive administration of GTN in this study. However, the treatment period lasted only 180 seconds, followed by 15 minutes of recovery, and the sequence of concentrations was randomized. This regimen most likely avoided the occurrence of nitrate tolerance in our study, as indicated by the unchanged blood flow response throughout the experiments.
In summary, we measured changes in regional myocardial function in the absence of systemic alterations and demonstrated that intracoronary infusion of NO donors evoked a small direct positive inotropic effect in vivo. The improvement in regional myocardial contractile function cannot be explained by the concomitant increase in coronary flow, suggesting that NO improves the contractile activity of the ventricular myocardium. The effective concentration of NO at the level of the cardiomyocytes was most likely much lower than the initially achieved intracoronary concentration of the NO donors, which might explain the absence of negative inotropic effects even at high concentrations of NO donors.
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Selected Abbreviations and Acronyms |
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Acknowledgments |
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This study was supported by the Deutsche Forschungsgemeinschaft, SFB 242 (Projekt A/11). The authors wish to thank Dr L. Keefer (National Cancer Institute, Frederick, Md) for providing DEA/NO. We also thank E. Hauschildt, H. Barthel, cand med, and D. Obal, cand med, for excellent technical assistance.
Received March 12, 1997; revision received June 3, 1997; accepted June 3, 1997.
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References |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
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1. Palmer RMJ, Ferrige AG, Moncada S. Nitric oxide release accounts for the biological activity of endothelium-derived relaxing factor. Nature. 1987;327:524-526.[Medline] [Order article via Infotrieve]
2. Strauer BE. Evidence for a positive inotropic effect of nitroglycerol on isolated human ventricular myocardium. Pharmacol Res Commun. 1971;3:377-383.
3. Strauer BE, Westberg C, Tauchert M. Studies on the inotropic actions of nitroglycerol on isolated ventricular muscle. Pflugers Arch. 1971;324:124-133.[Medline] [Order article via Infotrieve]
4. Korth M. Influence of glyceryl trinitrate on force of contraction and action potential of guinea-pig myocardium. Naunyn Schmiedebergs Arch Pharmacol. 1975;287:329-347.[Medline] [Order article via Infotrieve]
5. Kamelgard J, Crestanello JA, Fullerton D, Whitman GJ. Nitric oxide as a positive inotropic agent in isolated rat hearts. J Surg Res. 1995;59:482-484.[Medline] [Order article via Infotrieve]
6. Mohan P, Sys SU, Brutsaert DL. Positive inotropic effect of nitric oxide in myocardium. Int J Cardiol. 1995;50:233-237.[Medline] [Order article via Infotrieve]
7. Hacker A, Kottenberg K, Piper HM, Noack E, Kojda G. Positive effects of organic nitrates and NO-donors on cardiac contractile force. Circulation. 1995;92(suppl I):I-870. Abstract.
8.
Kojda G, Kottenberg K, Nix P, Schlüter KD, Piper
HM, Noack E. Low increase in cGMP induced by organic nitrates
and nitrovasodilators improves contractile response of rat
ventricular myocytes. Circ Res. 1996;78:91-101.
9.
Brady AJB, Warren JB, Poole-Wilson PA, Williams TJ,
Harding SE. Nitric oxide attenuates cardiac myocyte
contraction. Am J Physiol. 1993;265:H176-H182.
10.
Mohan P, Brutsaert DL, Paulus WJ, Sys SU.
Myocardial contractile response to nitric oxide and cGMP.
Circulation. 1996;93:1223-1229.
11. Nawrath H. Does cyclic GMP mediate the negative inotropic effect of acetylcholine in the heart? Nature. 1977;267:72-74.[Medline] [Order article via Infotrieve]
12. Balligand JL, Ungureanu D, Kelly RA, Kobzik L, Pimental D, Michel T, Smith TW. Abnormal contractile function due to induction of nitric oxide synthesis in rat cardiac myocytes follows exposure to activated macrophage-conditioned medium. J Clin Invest. 1993;91:2314-2319.
13.
Brady AJB, Poole-Wilson PA, Harding SE, Warren
JB. Nitric oxide production within cardiac myocytes
reduces their contractility in endotoxemia.
Am J Physiol. 1992;263:H1963-H1966.
14.
Finkel MS, Oddis CV, Jacob TD, Watkins SC, Hattler BG,
Simmons RL. Negative inotropic effects of cytokines on
the heart mediated by nitric oxide. Science. 1992;257:387-389.
15. Raff WK, Drechsel U, Scholtholt J, Lochner W. Effects of nitroglycerine on the heart. Pflugers Arch. 1970;317:336-343.[Medline] [Order article via Infotrieve]
16.
Crystal GJ, Gurevicius J. Nitric oxide does not
modulate myocardial contractility acutely in in situ
canine hearts. Am J Physiol. 1996;270:H1568-H1576.
17. Hare JM, Keaney JF, Balligand JF, Loscalzo J, Smith TW, Colucci WS. Role of nitric oxide in parasympathetic modulation of beta-adrenergic myocardial contractility in normal dogs. J Clin Invest. 1995;95:360-366.
18. Brodie BR, Grossman W, Mann T, McLaurin LP. Effects of sodium nitroprusside on left ventricular diastolic pressure-volume relations. J Clin Invest. 1977;59:59-68.
19.
Gregg DE. Effect of coronary perfusion
pressure and coronary flow on oxygen usage of the
myocardium. Circ Res. 1963;13:497-500.
20. Field L, Dilts RV, Ravichandran R, Lenhert G, Carnahan GE. An unusual stable thionitrite from N-acetyl-D,L-penicillamine: x-ray crystal and molecular structure of 2-(acetylamino)-2-carboxy-1,1-dimethylethyl thionitrite. J Chem Soc Chem Comm. 1978;1157:249-250.
21. Schlack W, Ebel D, Thämer V. Effect of inotropic stimulation on the synchrony of left ventricular wall motion in a dog model of myocardial stunning. Acta Anaesthesiol Scand. 1996;40:621-630.[Medline] [Order article via Infotrieve]
22. Gwirtz PA, Franklin D, Mass HJ. Modulation of synchrony of left ventricular contraction by regional adrenergic stimulation in conscious dogs. Am J Physiol. 1986;251:H490-H495.
23. Feelisch M, Noack E. Correlation between nitric oxide formation during degradation of organic nitrates and activation of guanylate cyclase. Eur J Pharmacol. 1987;139:19-30.[Medline] [Order article via Infotrieve]
24.
Stamler JS, Singel DJ, Loscalzo J. Biochemistry
of nitric oxide and its redox-activated forms.
Science. 1992;258:1898-1902.
25. Stamler JS. Redox signaling: nitrosylation and related target interactions of nitric oxide. Cell. 1994;78:931-936.[Medline] [Order article via Infotrieve]
26. Abel FL. Maximal negative dP/dt as an indicator of end of systole. Am J Physiol. 1981;240:H676-H679.
27.
Roan PG, Buja LM, Izquierdo C, Hashimi H, Saffer S,
Willerson JT. Interrelationships between regional left
ventricular function, coronary blood flow, and
myocellular necrosis during the initial 24 hours and 1 week after
experimental coronary occlusion in awake, unsedated
dogs. Circ Res. 1981;49:31-40.
28.
Theroux P, Franklin D, Ross J Jr, Kemper WS.
Regional myocardial function during acute coronary artery
occlusion and its modification by pharmacological agents in the
dog. Circ Res. 1974;35:896-908.
29. Brown BG. Dilation of coronary artery stenosis: a major mechanism of the effect of nitrates. Z Kardiol. 1983;72(suppl 3):77-81.
30. Morley D, Maragos CM, Zhang XY, Boignon M, Wink DA, Keefer LK. Mechanism of vascular relaxation induced by the nitric oxide (NO)/nucleophile complexes, a new class of NO-based vasodilators. J Cardiovasc Pharmacol. 1993;21:670-676.[Medline] [Order article via Infotrieve]
31. Vanderford PA, Wong J, Chang R, Keefer LK, Soifer SJ, Fineman JR. Diethylamine/nitric oxide (NO) adduct, an NO donor, produces potent pulmonary and systemic vasodilation in intact newborn lambs. J Cardiovasc Pharmacol. 1994;23:113-119.[Medline] [Order article via Infotrieve]
32.
Chung SJ, Fung HL. Identification of the
subcellular site for nitroglycerin
metabolism to nitric oxide in bovine coronary
smooth muscle cells. J Pharmacol Exp Ther. 1990;253:614-619.
33.
Salvemini D, Mollace V, Pistelli A, Anggard E, Vane
J. Metabolism of glyceryl trinitrate to nitric oxide
by endothelial cells and smooth muscle cells and its
induction by Escherichia coli
lipopolysaccharide. Proc Natl Acad Sci U S A. 1992;89:982-986.
34. Cederqvist B, Persson MG, Gustafsson LE. Direct demonstration of NO formation in vivo from organic nitrites and nitrates, and correlation to effects on blood pressure and to in vitro effects. Biochem Pharmacol. 1994;47:1047-1053.[Medline] [Order article via Infotrieve]
35. Ahlner J, Andersson RGG, Torfgard K, Axelsson KL. Organic nitrate esters: clinical use and mechanisms of actions. Pharmacol Rev. 1991;43:351-423.[Medline] [Order article via Infotrieve]
36. Bassenge E, Stewart DJ. Effects of nitrates in various vascular sections and regions. Z Kardiol. 1986;75(suppl 3):1-7.
37.
Schulz R, Guth BD, Heusch G. No effect of
coronary perfusion on regional myocardial function within the
autoregulatory range in pigs: evidence against the Gregg
phenomenon. Circulation. 1991;83:1390-1403.
38. Kojda G, Brixius K, Kottenberg K, Nix P, Schlüter KD, Piper HM, Noack E. The new NO donor SPM3672 increases cGMP and improves contraction in rat cardiomyocytes and isolated heart. Eur J Pharmacol. 1995;284:315-319.[Medline] [Order article via Infotrieve]
39.
Paulus W, Vantrimpont PJ, Shah AM. Acute effects
of nitric oxide on left ventricular relaxation and
diastolic distensibility in humans: assessment by
bicoronary sodium nitroprusside infusion.
Circulation. 1994;89:2070-2078.
40.
Stamler JS, Loh E, Roddy MA, Currie MG, Creager
MA. Nitric oxide regulates basal systemic and pulmonary
vascular resistance in healthy humans. Circulation. 1994;89:2035-2040.
41. Widdop RE, Gardiner SM, Kemp PA, Bennett T. The influence of atropine and atenolol on the cardiac haemodynamic effects of NG-nitro-L-arginine methyl ester in conscious, Long Evans rats. Br J Pharmacol. 1992;105:653-656.[Medline] [Order article via Infotrieve]
42.
Leite-Moreira AF, Mohan P, Sys SU, Brutsaert DL.
Myocardial positive inotropic effect of dibutyryl-cyclic GMP
in-vivo. Eur Heart J. 1994;15:145. Abstract.
43. Guth BD, Schulz R, Heusch G. Evaluation of parameters for the assessment of regional myocardial contractile function during asynchronous left ventricular contraction. Basic Res Cardiol. 1990;85:550-562.[Medline] [Order article via Infotrieve]
44.
Schlack W, Schäfer S, Thämer V. Left
stellate ganglion block impairs left ventricular
function. Anesth Analg. 1994;79:1082-1088.
45. Braunwald E, Ross J Jr. Handbook of Physiology: Cardiovascular System: The Heart. Bethesda, Md: American Physiological Society; 1979:544-555.
46. Cowae JC. Nitrate tolerance. Int J Cardiol. 1986;12:1-19.[Medline] [Order article via Infotrieve]
47. Miyauchi N, Takahashi M, Fujioka H, Kinoshita M. Dissociation of hemodynamic and coronary arterial tolerance to nitroglycerin in dogs. J Cardiovasc Pharmacol. 1993;21:767-773.[Medline] [Order article via Infotrieve]
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