Abstract 17080: The Anesthetized Rat Model of Exercise Faithfully Simulates Respiratory Abnormalities in Chronic Heart Failure
Background: Abnormal respiration during exercise is one of the major manifestations and a powerful predictor of survival in chronic heart failure (CHF). There have not been proposed the appropriate animal model to investigate the mechanism of respiratory abnormalities in CHF during exercise. In this study, we developed an experimental model using anesthetized CHF rats to evaluate exercise-induced abnormal respiration and central chemoreflex control function during exercise in CHF.
Methods: We used anesthetized 16 weeks old rats with/without myocardial infarction induced CHF. To mimic exercise, we induced muscle contraction by stimulating bilateral distal sciatic nerves. We recorded the respiratory change in response to sciatic nerve stimulation (SNS) with ramp (5 Hz, 0.01 Volts/sec) and step (5 Hz, 0.5 Volts) protocols. We also evaluated the change of the central chemosensitivity (ventilatory response to partial pressure of carbon dioxide in arterial blood; PaCO2) by CO2 gas inhalation (0, 3 and 5%) during exercise in normal and CHF.
Results: In ramp protocol, SNS significantly increased minute ventilation (VE) in CHF to a greater extent than in that of normal (normal 155.2±27.9, CHF 211.2±48.6 mL/min, p<0.01). CHF markedly steepened the VE-carbon dioxide production relationship (VE/VCO2 slope) (normal 26.8±12.7, CHF 38.5±5.9, p<0.05) (Fig. 1). CHF shifted the relationship of tidal volume (TV) to respiratory rate (RR) rightward reflecting the rapid and shallow breathing during exercise (Fig. 2). The SNS-induced upward shift of the VE-PaCO2 line observed in CHF indicated that exercise-related respiratory abnormalities arise from pathophysiological change in the central chemoreflex control (Fig. 3).
Conclusion: Anesthetized rat exercise model simulated respiratory abnormalities in CHF reasonably well. It will provide us an opportunity to clarify the physiological mechanisms of exercise-induced abnormal respiration in CHF.
Author Disclosures: A. Nishizaki: None. K. Saku: None. T. Miyamoto: None. T. Kishi: None. K. Sunagawa: None.
- © 2015 by American Heart Association, Inc.