Meeting Abstract

14.2  Jan. 4  Growth, Metabolism and Exercise Endurance of American Alligator (Alligator mississippiensis) with and without Cardiac Shunt EME, John*; GWALTHNEY, June; OWERKOWICZ, Tomasz; BLANK, Jason/M; HICKS, James/W; University of California, Irvine; University of California, Irvine; University of California, Irvine; University of California, Irvine; University of California, Irvine jeme@uci.edu

All non-avian reptiles are capable of cardiac shunting, and crocodilians have two completely separate ventricles, allowing for only a right-to-left (R-L) shunt. This unique reptilian design allows for surgical removal of the ability to R-L shunt and inference of physiological function in its absence. Cardiac shunting is generally considered to have adaptive importance, however, without experimental evidence of reduced fitness, adaptive significance cannot be assumed a priori. We surgically removed the ability for R-L shunting in hatchling American alligator (5-months old; January-February 2006). We show that distal occlusion of the left aortic arch (LAo) is insufficient to eliminate shunting completely. It is also necessary to tie off the LAo proximally, at the ventricular base of the LAo and Right aortic arch below the foramen of Panizza. We are measuring body mass and snout-vent, total and head lengths of surgically modified (�experimental�), sham, and control animals of similar age (N = 36, each group) every two weeks. Each group is further divided into 3 exercise sub-groups (N = 12, each sub-group): run, swim, and sedentary. Animals in the run and swim groups are exercised to exhaustion every other day on a treadmill or in a swim flume, respectively. Preliminary growth trajectories (i.e., slope) appear to be diverging between groups; however, exercise endurance does not differ between sub-groups. In addition, measurements of SMR, VO2max, specific dynamic action, and exercise endurance (swimming and running) will be presented. (This work is supported by NSF Grant IOB 0445680 to JWH)