ADAPTIVE RESPONSES TO FEEDING IN BURMESE PYTHONS - PAY BEFORE PUMPING

Burmese pythons normally consume large meals after long intervals, We measured gut contents, O-2 consumption rates, small intestinal brush-b order uptake rates of amino acids and glucose, organ masses and blood chemistry in pythons during the 30 days following ingestion of meals e quivalent to 25 % of their body mass. Within 1-3 days after ingestion, O-2 consumption rates, intestinal nutrient uptake rates and uptake ca pacities peaked at 17, 6-26 and 11-24 times fasting levels, respective ly, Small intestinal mass doubled, and other organs also increased in mass, Changes in blood chemistry included a 78 % decline in P-O2 and a large 'alkaline tide' associated with gastric acid section (i.e. a ri se in blood pH and HCO3- concentrations and a fall in Cl- concentratio n), All of these values returned to fasting levels by the time of defe cation at 8-14 days, The response of O-2 consumption (referred to as s pecific dynamic action, SDA) is the largest, and the upregulation of i ntestinal nutrient transporters the second largest, response reported for any vertebrate upon feeding, The SDA is as large as the factorial rise in O-2 consumption measured in mammalian sprinters and is sustain ed for much longer, The extra energy expended for digestion is equival ent to 32 % of the meal's energy yield, with much of it being measured before the prey energy was absorbed.