Meeting Abstract
74.2 Monday, Jan. 6 08:15 Metabolic and cardiac correlates of hatching in an ectothermic archosaur DZIALOWSKI, E.M.*; SOTHERLAND, P.R.; GOY SIRSAT, S.K.; SIRSAT, T.S.; Univ. of North Texas; Kalamazoo College; Univ. of North Texas; Univ. of North Texas edzial@unt.edu
Though metabolic capacity is augmented in birds when endothermy develops, non-avian archosaurs remain ectothermic throughout their lives and lack metabolic augmentation. We have shown in the Pekin duck (Anas pekin) that mitochondrial respiration increases in the left ventricle of the heart upon hatching and in association with attainment of endothermic capacity. In the present study, and largely as a foil to our experiment conducted in Pekin duck, we examined whole animal metabolism and cardiac mitochondrial respiration of right and left ventricles in prehatch and neonate American alligators (Alligator mississippiensis). Animals were examined at 80% development (stage 25), 90% development (stage 27), day 0, day 1, and day 7 days post hatch (dph). Oxygen consumption was measured at 32oC and 25oC and was significantly lower at 25oC, typical of an ectothermic phenotype. No significant differences between mitochondrial respiration of the right and left ventricles at the LEAK and OXPHOS (CI and CI+CII) were seen. There was also no significant difference in mitochondrial respiration as the animals aged. Contrary to duck hatchlings, heart mass as a fraction of body mass did not change with hatching. These results in alligator suggest that the increase of mitochondrial activity in the left ventricle seen previously in ducks is not merely a facet of the hatching and aging process, but is a physiological change necessary for metabolic maturation of endothermic species.
