AJP - Gastrointestinal and Liver Physiology, Vol 255, Issue 3 339-G345, Copyright © 1988 by American Physiological Society
Glucose enhancement of transcellular calcium transport in the intestine
K. M. Carroll, R. J. Wood, E. B. Chang and I. H. Rosenberg
Department of Medicine, University of Chicago, Illinois 60637.
Glucose stimulates calcium transport in vitro in rat duodenal tissue and
isolated enterocytes. Under short-circuited conditions, glucose increased
mucosal to serosal calcium flux (JCa(m----s)) without altering serosal to
mucosal calcium flux (JCa(s----m)) in the duodenum, the primary site of
active calcium absorption in the rat small intestine. The half-maximal dose
(ED50) of the glucose stimulatory effect was less than 1 mM, and an
increase in JCa(m----s) of 80% over control was seen at a glucose
concentration of 50 mM. Glucose did not increase calcium flux in the ileum
where active calcium absorption is minimal. Glucose stimulated net calcium
uptake by 35% in isolated duodenal enterocytes. Glucose did not alter
calcium efflux from preloaded enterocytes suspended in calcium-free buffer.
Glucose enhancement of net calcium uptake in enterocytes was not caused by
altered cell membrane integrity or functional viability. The
nonmetabolizable glucose analogue alpha-methylglucoside did not stimulate
calcium transport. Our findings suggest that glucose can stimulate
intestinal calcium absorption, at least partially, by enhancing
transcellular calcium transport and that cellular glucose metabolism is
necessary for stimulation of this route of calcium transport.
