EFFECTS OF MEAL SIZE ON POSTPRANDIAL RESPONSES IN JUVENILE BURMESE PYTHONS (PYTHON MOLURUS)

Pythons were reported previously to exhibit large changes in intestina l mass and transporter activities on consuming meals equal to 25% of t he snake's body mass. This paper examines how those and other adaptive responses to feeding vary with meal size (5, 25, or 65% of body mass) . Larger meals took longer to pass through the stomach and small intes tine. After ingestion of a meal, O-2 consumption rates rose to up to 3 2 times fasting levels and remained significantly elevated for up to 1 3 days. This specific dynamic action equaled 29-36% of ingested energy . After 25 and 65% size meals, plasma Cl- significantly dropped, where as plasma CO2, glucose, creatinine, and urea nitrogen increased as muc h as a factor of 2.3-4.2. Within 1 day the intestinal mucosal mass mor e than doubled, and masses of the intestinal serosa, liver, stomach, p ancreas, and kidneys also increased. Intestinal uptake rates of amino acids and of D-glucose increased by up to 43 times fasting levels, whe reas uptake capacities increased by up to 59 times fasting levels. Mag nitudes of many of these responses (O-2 consumption rate, kidney hyper trophy, and D-glucose and L-lysine uptake) increased with meal size up to the largest meals studied; other responses (Na+-independent L-leuc ine uptake, plasma Cl-, and organ masses) plateaued at meals equal to 25% of the snake's body mass; and still other responses (nutrient upta ke at day 1, passive glucose uptake, and plasma protein and alkaline p hosphatase) were all-or-nothing, being independent of meal size betwee n 5 and 65% of body mass. Pythons undergo a wide array of postprandial responses, many of which differ in their sensitivity to meal size.