Effect of pentobarbital anesthesia on contractile performance and oxygen-consumption of perfused rat heart.

Rat hearts were isolated from two groups of animals: I, Control (C); and II, Anesthetized with sodium pentobarbital (Nembutal) (P) 5 mg/100 g body weight prior to decapitation and perfused by modified Langendorff-technique. Left ventricular mechanical performance (LVSP, LVPD, dp/dtmax) and O2 consumption of P hearts was identical to that of C hearts. P hearts exhibited significantly lower coronary resistance and higher spontaneous heart rate. During electrical pacing (240--480/min) C and P hearts showed similar increase of mechanical performance. In sharp contrast to C hearts, P hearts were completely insensitive to threefold elevation of perfusate Ca2+ (from 1.3 to 3.9 mM). Experimental results suggest that pentobarbital anesthesia exerts a long-lasting effect on the isolated myocardium, which should be considered if tissues are isolated from animals treated by this drug.