|
|
||||||||
AJP - Gastrointestinal and Liver Physiology, Vol 242, Issue 2 79-G84, Copyright © 1982 by American Physiological Society
ARTICLES |
T. E. Machen, M. J. Rutten and E. B. Ekblad
The involvement of cAMP as a second messenger for histamine-induced H+ secretion was studied in a physiologically active, in vitro preparation of piglet gastric mucosa. During the first 5--10 min of stimulation with either histamine or the cAMP phosphodiesterase inhibitor 3-isobutyl-1,4-methylxanthine (IBMX), increases (greater than or equal to 5-fold) in tissue cAMP content [(c-AMP]) were well correlated with the characteristic decrease in transepithelial resistance (R); these changes precede H+ secretion by several minutes. Control experiments indicate that, during these treatments, tissue [cAMP] is dominated by the [cAMP] of oxyntic cells alone; change in R and H+ are also related to activity of these cells alone. At the steady state (45 min), histamine and IBMX caused equivalent increases in H+ and decreases in R, but [cAMP] was markedly different in the two cases. With IBMX [cAMP] was elevated at least fivefold, whereas with histamine [cAMP] was less than or equal to 50% above resting levels. The tissue is also stimulated by exogenous additions of dibutyryl cAMP. A histamine-sensitive adenylate cyclase was present in isolated, purified oxyntic cells. The histamine sensitivity of the cyclase was very similar to that which the intact tissue exhibits for histamine-induced changes in H+ and R. The cyclase activity was blocked by cimetidine but not by promethazine. We conclude that during stimulation histamine activates a histamine (H2)-sensitive adenylate cyclase of oxyntic cells, and there is a rapid increase in cellular [cAMP] that is involved in activation of H+ transport and other associated changes of oxyntic cells. An active phosphodiesterase is responsible for reducing [cAMP] to a level much below the "peak" value. Other cellular factors (e.g. protein kinases and Ca2+-calmodulin) must also be involved in the maintenance of the stimulated state of oxyntic cells.
This article has been cited by other articles:
![]() |
S. E. Mettler, S. Ghayouri, G. P. Christensen, and J. G. Forte Modulatory role of phosphoinositide 3-kinase in gastric acid secretion Am J Physiol Gastrointest Liver Physiol, September 1, 2007; 293(3): G532 - G543. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |