Feeding alters blood flow patterns in the American alligator (Alligator mississippiensis)

The crocodilian cardiovascular design with a four-chambered heart and a left aorta that emerge from the right ventricle allows blood to be shunted away from the lungs, a right-to-left (R-L) shunt. The adaptive significance of this R-L shunt remains both poorly understood and controversial with particular debate on its putative role during digestion. Here we measure blood flow patterns in the right aorta (RAo), left aorta (LAo) and the coeliac artery (CoA) of undisturbed American alligators (Alligator mississippiensis) during fasting and throughout most of the digestive period. Digestion doubled blood flow in the RAo (10.1±0.9 to 20.7±1.5mlmin^-1kg^-1), whereas LAo increased approximately 3-fold (3.8±0.6 to 12.2±2.1mlmin^-1kg^-1). Blood flow in the CoA increased more than four-fold during digestion (3.0±0.6 to 13.3±1.6mlmin^-1kg^-1). The rise in blood flows was achieved by a doubling of heart rate (18.5±3.3 to 37.8±3.6mlmin^-1kg^-1). Maximal flows measured in all arteries and heart rate occurred in the first hour of the postprandial period and continued for the next 7h.