AJP - Regulatory, Integrative and Comparative Physiology, Vol 269, Issue 6 1475-R1480, Copyright © 1995 by American Physiological Society
Alterations of energy and substrate metabolism in rats with large and sustained changes in daily food intake
J. F. Wang and H. S. Koopmans
Department of Medical Physiology, University of Calgary, Alberta, Canada.
Energy expenditure was measured in one-way crossed-intestine rats by use of
indirect calorimetry to examine the role of energy metabolism in body
weight control. The intestinal surgery was done according to Koopmans
(Brain Res. Bull. 14: 595-603, 1985). The food-losing rats increased daily
food intake from 70.8 to 126.3 g/day, whereas their partners decreased
intake from 67.1 to 38.7 g/day (P < 0.001). Compared with levels before
surgery, the food-losing rats showed slightly increased O2 consumption
(1.31 vs. 1.28 1.h-1.kg-1) and metabolic rate (6.62 vs. 6.39 kcal.h-1.kg-1)
and largely increased CO2 production (1.31 vs. 1.22 l.h-1.kg-1, P <
0.01), whereas in their food-gaining partners O2 consumption (1.12 vs. 1.25
l.h-1.kg-1, P < 0.01) and metabolic rate (5.76 vs. 6.26 kcal.h-1.kg-1)
were significantly decreased. Respiratory quotients were higher in the
food-gaining rats than in their partners (1.076 vs. 0.999, P < 0.01),
indicating more fatty acid synthesis. These results suggest that daily food
intake and energy expenditure increase and decrease together, despite the
fact that about the same amount of food has been absorbed from the
intestines of each rat.
