AJP - Gastrointestinal and Liver Physiology, Vol 245, Issue 5 624-G627, Copyright © 1983 by American Physiological Society
Calcium flux in vivo in the rat duodenum and ileum during pregnancy and lactation
M. Toraason
Intestinal calcium transport was examined in nonpregnant, pregnant,
lactating, and 100 ng 1,25-dihydroxyvitamin D3-dosed rats. Solutions
containing 150 mM NaCl, 1 mM Ca, and 0.1 microCi 45Ca were recirculated in
vivo through the duodenum and ileum to determine calcium efflux from the
lumen, influx into the lumen, and net absorption. In the duodenum of the
nonpregnant control rats, efflux of calcium was greater than influx,
resulting in net absorption of calcium. In the ileum, calcium efflux and
influx were equivalent and there was little net movement of calcium.
1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] significantly increased efflux and
net absorption of calcium in the duodenum without affecting influx. In the
ileum 1,25(OH)2D3 had no effect on calcium flux. During pregnancy and
lactation there was a marked increase in mucosal tissue, and expression of
transport data per centimeter of intestine gave different results than
transport expressed per gram of dry mucosal tissue. Per centimeter of
intestine, duodenal efflux and net absorption, but not influx, increased
significantly during pregnancy and to greater extent during lactation. Per
gram of dry mucosa, duodenal efflux and net absorption were increased
significantly only during lactation, and the increase was comparable with
that observed in 1,25(OH)2D3-dosed rats. In the ileum of pregnant and
lactating rats, efflux and influx expressed per centimeter of intestine
increased to approximately the same extent, and net movement of calcium
remained unchanged from the control level. Expression of ileal transport
data per gram of dry mucosa resulted in no significant difference in
calcium movement during pregnancy and lactation.(ABSTRACT TRUNCATED AT 250
WORDS)
