AJP - Gastrointestinal and Liver Physiology, Vol 241, Issue 3 215-G221, Copyright © 1981 by American Physiological Society
Effects of somatostatin on intestinal calcium transport in the rat
M. J. Favus, M. Berelowitz and F. L. Coe
The addition of somatostatin (SRIF) to rat descending colon in vitro
increased the calcium secretory flux from serosa to mucosa (Js leads to m)
and reduced tissue short-circuit current (Isc) but did not alter the
absorptive flux from mucosa to serosa (Js leads to m). Js leads to m
increased by 37% at 10(-9) M SRIF and by 48% at 10(-6) M. The response to
SRIF was not altered by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and SRIF
did not interfere with stimulation of calcium Jm leads to s by 1,25(OH)2D3.
Removal of sodium from the buffer abolished the stimulation of Js leads to
m by SRIF without reducing basal Js leads to m. Secretory fluxes of
mannitol and calcium were strongly correlated in the presence and absence
of SRIF, suggesting that SRIF stimulates a paracellular transepithelial
pathway for calcium. In the duodenum, SRIF altered neither calcium Js leads
to m nor Isc. In the ileum, calcium Js leads to m increased and Isc
decreased, as in the colon, but only by 28 and 12%, respectively. The
maximal change in calcium Js leads to m caused by SRIF in these three
intestinal segments was negatively correlated with the tissue concentration
of immunoreactive SRIF. These results suggest that intestinal calcium
secretion could, in part, be regulated by intestinal SRIF.
