66.1 Jan. 7 Spatial and temporal variation in the pH of the gastrointestinal tract of the Burmese python SECOR, S.M.*; BOBACK, S.M.; LIGNOT, J.-H.; University of Alabama; University of Alabama; Louis Pasteur University email@example.com
Feeding triggers the rapid production of gastric acid for the Burmese python, lowering stomach pH from 7 to 2 within 24 hours. Unknown is the extent that the adjoining esophagus and small intestine are able to buffer this large flux in acid production. Therefore we measured luminal pH at 16 sites within the gastrointestinal tract of fasted pythons and of fed pythons at nine time points (0.25 – 15 days) following their consumption of a rodent meal equaling 25% of snake body mass. For all time periods, including fasting, there was significant variation in luminal pH throughout the GI tract. Even for fasted snakes, pH varied from 6.5 (stomach) to 7.6 (cecum). For fed snakes, pH was the lowest in the stomach (2 – 3), intermediate in the distal esophagus, proximal stomach, and distal large intestine (5 – 6.7) and highest in the esophagus, distal small intestine, cecum, and proximal large intestine (7 – 8). Across sampling periods, we detected no significant change in luminal pH for the proximal esophagus, middle and distal small intestine, cecum, and large intestine. In contrast, the distal esophagus, stomach, and proximal small intestine each varied in luminal pH among sampling times, a function of the postprandial production of gastric acid and the downregulation of acid production once gastric digestion had ceased. The very sharp gradient in pH (2 to 5-6) between the stomach and the distal esophagus and proximal small intestine demonstrates the tremendous buffering capacity of these latter two tissues. The high pH of cecal contents (> 7.4) suggests the absence of significant microbial fermentation occurring in the cecum.