Meeting Abstract

P1.106  Thursday, Jan. 3  Postprandial response of ventricular mass and metabolic enzyme activities for the Burmese pythons Python molurus COPELAND, D.L.*; RODNICK, K.J.; EARLEY, R.L.; SECOR, S.M.; California State University, Fresno; Idaho State University; California State University, Fresno; University of Alabama, Tuscaloosa dlcevo1@yahoo.com

Pythons experience unprecedented increases in metabolism and cardiac function during digestion. To ascertain the postprandial response of cardiac metabolism, we studied postfeeding changes in ventricular mass, metabolite concentrations, and enzyme activities for the Burmese python (Python molurus). We measured from fasted and fed pythons, plasma concentrations of glucose and lactate and from dissected ventricles, wet mass, glucose, glycogen, and lactate concentrations, and activities of pyruvate kinase (PK), hexokinase (HK), citrate synthase (CS), and β-hydroxylacyl CoA dehydrogenase (HOAD). Plasma glucose levels did not change postfeeding, whereas plasma lactate levels doubled within 1 day after feeding. By day 2 of digestion, pythons had experienced a 40% increase in ventricular mass. Ventricular glucose and glycogen levels decreased by 70% and 40% after feeding, whereas there was no postfeeding change in cardiac lactate. Activities of PK and HK did not vary significantly among sampling periods, whereas CS and HOAD activities significantly declined after 1 day of digestion. However, ventricular capacity for CS (product of ventricle mass and mass-specific activity) did not vary among sampling periods. The capacity for HOAD was significantly greater at day 10 compared to earlier sampling times. These results suggest that the adaptive strategy of the python heart is to maintain adequate metabolic capacity when fasting in order to meet the rapid increase in cardiac output and metabolism after feeding, and to enhance cardiac output during digestion by increasing ventricular size.