Abstract 12: The Influence Of Sex On Endogenous Adenosine Production And The Occurrence Of Ventricular Fibrillation During Myocardial Ischemia
Background: Endogenous adenosine (ADO) is cardioprotective during acute ischemic insult. Myocardial ischemia can cause ventricular arrhythmias and is used to induce ventricular fibrillation (VF) in some animal models of cardiac arrest. Recent evidence suggests that sex may influence VF decay and the rate of ROSC in porcine VF. We sought to determine the effect of animal sex on ADO production and the occurrence of VF during left anterior descending artery (LAD) occlusion in dogs. Our null hypothesis was there would be no difference between male and female animals.
Methods: This was a secondary analysis of previously published data from an IACUC approved protocol. Twenty-nine anesthetized mongrel dogs (15 M, 14 F) were prepared in a standard fashion. Hemodynamic parameters were monitored continuously during the experiment. Blood from the great cardiac vein was sampled for endogenous ADO concentration at baseline and at 1, 2, 3, 5, 7, and 10 minutes of LAD occlusion. Plasma ADO concentration was determined by radioimmunoassay. Group comparisons were assessed using descriptive statistics, Student’s t-test for continuous variables and Fisher’s Exact Test for dichotomous variables. Proportions with 95% confidence intervals were calculated for the AUC and the rate of VF induction.
Results: Baseline characteristics between the two groups were the same. VF occurred in 14 of the 29 animals in the primary study, with ADO concentration being higher in the non-VF group compared to the VF group (p=0.026). Between the sexes, the proportion of males in the non-VF group was 10/15 [0.66 (95%CI=0.43,0.91)] and in the VF group it was 5/14 [0.35 (95%CI=0.11,0.61)]. ADO concentrations in the male animals were slightly higher [AUC=924(95%CI=476,1372)] compared to females [AUC=659(95%CI=124,1195)] at all points during LAD occlusion. The small sample size is a limitation of this study.
Conclusions: In this study, there was a trend toward male dogs generating higher ADO levels and having lower fibrillation rates when compared to females but the difference was not statistically significant. Further clarification of the influence of sex on endogenous ADO in ischemia-induced VF is needed. Meanwhile, investigators using an ischemia model of VF may want to control for animal sex.