Effects of meal size on post-prandial responses in juvenile burmese
pythons (python molurus).
Secor, Stephen M., and Jared Diamond.
Department of Physiology, UCLA School of Medicine, Los Angeles,
California 90095-1751
APStracts 3:0370R, 1996.
Pythons were reported previously to exhibit large changes in
intestinal mass and transporter activities upon consuming meals equal
to 25% of the 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 intestine. After ingestion of a meal, O2
consumption rates rose to up to 32 times fasting levels and remained
significantly elevated for up to 13 days. This specific dynamic
action equalled 29 to 36% of ingested energy. After 25% and 65% size
meals, plasma Cl significantly dropped, whereas plasma CO2, glucose,
creatinine, and urea nitrogen increased as much as a factor of 2.3
4.2. Within 1 day the intestinal mucosal mass more than doubled, and
masses of the intestinal serosa, liver, stomach, pancreas, and
kidneys also increased. Intestinal uptake rates of amino acids and of
D-glucose increased by up to 43 times fasting levels, while uptake
capacities increased by up to 59 times fasting levels. Magnitudes of
many of these responses (O2, kidney hypertrophy, D-glucose and L
-lysine uptake) increased with meal size up to the largest meals
studied; other responses (Na+-independent L-leucine uptake, plasma
Cl-, and organ masses) plateaued at meals equal to 25% of the snake's
body mass; and still other responses (nutrient uptake at day 1,
passive glucose uptake, plasma protein and alkaline phosphatase) were
all-or-nothing, being independent of meal size between 5 and 65% of
body mass. Pythons undergo a wide array of post-prandial responses,
many of which differ in their sensitivity to meal size.
Received 22 May 1996; accepted in final form 3 October 1996.
APS Manuscript Number R284-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996