Background: Although abnormal respiration during exercise is a powerful predictor of survival in chronic heart failure (CHF), the lack of appropriate animal models which represent respiratory abnormalities limits mechanistic investigations. In this study, we developed an anesthetized rat model of exercise.Methods: We used anesthetized Sprague-Dawley rats with/without CHF. To mimic exercise, we induced muscle contraction by stimulating bilateral sciatic nerves (SNS). We recorded the respiratory change in response to SNS with ramp (5 Hz, 0.01 volts/sec) protocols. Results: SNS significantly increased minute ventilation (VE) in CHF to a greater extent than in that of normal (Normal 66.5±12.8 mL/min vs. CHF 100.9±12.5 mL/min, p<0.05). The VE/VCO2 slope was significantly higher in CHF than Normal (Normal 26.8±12.7 vs CHF 38.5±5.9, p<0.05). CHF shifted the RR-TV relationship rightward indicating the rapid and shallow ventilation. Conclusion: Anesthetized rat exercise model simulated respiratory abnormalities in CHF reasonably well.
