P2.93 Thursday, Jan. 5 Adaptive regulation of gastrointestinal form and function for the diamondback rattlesnake. MENZEL, Evan J.*; NICHOLAS, Bailey; DENARDO, Dale F.; SECOR, Stephen M.; University of Alabama; University of Alabama; Arizona State University; University of Alabama email@example.com
Snakes exhibit an adaptive interplay between feeding frequency and the extent that they modulate gastrointestinal (GI) performance with feeding and fasting. Snakes that feed relatively frequently in the wild modestly regulate intestinal performance with each meal, whereas infrequently feeding species widely regulate intestinal form and function with the start and completion of digestion. We tested this adaptive hypothesis by examining postprandial responses in GI morphology and function for the western diamondback rattlesnake (Crotalus atrox). This rattlesnake feeds relatively infrequently in the wild given its sit-and-wait foraging behavior and hence is predicted to significantly regulate GI form and function with feeding. Luminal pH throughout the GI tract was relatively neutral (6-7.7) for fasting snakes. Rodent meals (25% of body mass) generated significant decreases in gastric pH (2-3) at 12 h and 2 d postfeeding, while other portions of the GI tract did not change in pH. Feeding resulted in a doubling of liver mass, tripling of small intestinal mass, a 76% increase in kidney mass, and a 73% reduction in the mass of the gall bladder. Rattlesnakes experienced with feeding 60%, 100%, and 120% increases in intestinal mucosal thickness, enterocyte volume, and microvillus length, respectively. We found feeding to induce significant increases in the specific activities and total tissue capacities of pancreatic trypsin and amylase and intestinal aminopeptidase and maltase. Western diamondback rattlesnakes experience the predicted wide regulation of gastrointestinal performance common to snakes that feed infrequently.