The effect of lumenal epidermal growth factor on enterocyte glucose
and proline transport.
Hardin, James A., Jason K. Wong, Christopher I. Cheeseman, and D.
Grant Gall.
Gastrointestinal Research Group, Health Sciences Centre, University
of Calgary, Calgary, Alberta, Canada and 1Department of Physiology,
University of Alberta, Edmonton, Alberta, Canada
APStracts 3:0014G, 1996.
The effect of lumenal epidermal growth factor (EGF; 60 ng/ml) and
tyrphostin 51 (TYR; 10 [mu]M), a tyrosine kinase inhibitor, on rabbit
jejunal brush border and basolateral membrane transport was
investigated. In separate experiments, the effect of EGF, EGF and
tyrphostin, or tyrphostin alone was examined in in vivo loops. In
addition, sodium permeability in brush border membrane vesicles and
the effect of Ca++ channel blockade on EGF-stimulated glucose uptake
was examined. Luminal EGF significantly (p<0.0001) increased the
Vmax for glucose and proline uptake in brush border membrane
vesicles. Tyrphostin and Ca++ channel blockade completely abolished
the EGF induced increase in glucose transport and in the case of
tyrphostin resulted in a significant reduction in Vmax compared to
controls (p<0.0001). Km did not differ in any experimental
group. EGF had no effect on brush border sodium permeability or
basolateral membrane glucose transport. The findings indicate a role
for EGF in the acute regulation of jejunal brush border membrane
nutrient uptake. Furthermore, tyrosine kinase activity appears to be
involved both in mediating EGF-induced alterations in transport
function and in the maintenance of basal brush border membrane
function.
Received 2 May 1995; accepted in final form 21 December 1995.
APS Manuscript Number G180-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 22 January 96