Premium
The role of cyclic AMP in the control of sugar transport across the brush‐border and basolateral membranes of rat jejunal enterocytes
Author(s) -
Sharp PA,
Debnam ES
Publication year - 1994
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.1994.sp003753
Subject(s) - enterocyte , brush border , adenylate kinase , medicine , vesicle , epithelial polarity , cyclase , chemistry , glucose transporter , endocrinology , glucagon , biology , biochemistry , small intestine , membrane , insulin , stimulation , receptor
Although the involvement of the adenylate cyclase system with glucose transport in the small intestine is poorly understood, there is increasing evidence that cyclic AMP stimulates sugar uptake. In order to study further the effects of cyclic AMP on this process, we have measured glucose accumulation by brush‐border and basolateral membrane vesicles prepared from villus enterocytes following exposure of these cells to cyclic AMP and theophylline. Brush‐border vesicles derived from enterocytes incubated with cyclic AMP and theophylline accumulated significantly more glucose over a wide range of sugar concentrations, suggesting a change in maximum velocity of the transport system. Glucose uptake by basolateral vesicles was increased at low, but not at high sugar concentrations. Incubation of isolated enterocytes with pancreatic glucagon at concentrations known to stimulate sugar transport by these cells significantly increased enterocyte levels of cyclic AMP. Treatment with glucagon or cyclic AMP resulted in significant hyperpolarization of the potential difference across the brush‐border membrane, an important driving force for Na(+)‐sugar cotransport. The response to glucagon and cyclic AMP appears to be caused by a decrease in Na+ permeability of the mucosal membrane. Taken together, these results suggest that cyclic AMP is a mediator of the actions of glucagon on enterocytes and provide further evidence for a role of cyclic AMP in the modulation of sugar transport across the intestinal enterocyte.