Effects of angiotensin II on intestinal absorption
Effects of angiotensin II on intestinal absorption
Studies were undertaken to investigate the ionic requirements for the stimulation of fluid transport by angiotensin II across the rat small intestine in vivo. Results indicated that luminal HCO3, Ca and Mg are not necessary in mediating the response and that HC03 is not a prerequisite for this action of the hormone.Investigation into the mechanism of action of angiotensin on intestinal fluid transfer was extended to test the possibility that this effect of the hormone is mediated via the release of noradrenaline from nerve endings innervating the mucosa. Both angiotensin and noradrenaline enhance net fluid absorption, and several similarities between the two agents were found to exist in mediating this event. The response to both agents is blocked by adrenergic antagonists and also by the protein synthesis inhibitor cycloheximide. Furthermore, cyclic AMP does not appear to be involved in mediating either angiotensin or noradrenaline stimulated fluid absorption. Since angiotensin is well known to release noradrenaline in other peripheral systems it seems possible that angiotensin-stimulated fluid transport is mediated via release of noradrenaline, since the angiotensin response was lost in animals pretreated with reserpine. The converse that noradrenaline enhances fluid absorption through the release of angiotensin has been eliminated since the response to noradrenaline is maintained in animals whose renal source of renin is removed by prior bilateral nephrectomy. Further support is lent to the proposal that the angiotensin action is mediated, by noradrenaline release' since it was found that in an in vitro intestinal preparation tyramine, an agent that releases endogenous noradrenaline, enhances net absorption of Na.
University of Southampton
Stewart, Christopher Paul
1979
Stewart, Christopher Paul
Stewart, Christopher Paul
(1979)
Effects of angiotensin II on intestinal absorption.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Studies were undertaken to investigate the ionic requirements for the stimulation of fluid transport by angiotensin II across the rat small intestine in vivo. Results indicated that luminal HCO3, Ca and Mg are not necessary in mediating the response and that HC03 is not a prerequisite for this action of the hormone.Investigation into the mechanism of action of angiotensin on intestinal fluid transfer was extended to test the possibility that this effect of the hormone is mediated via the release of noradrenaline from nerve endings innervating the mucosa. Both angiotensin and noradrenaline enhance net fluid absorption, and several similarities between the two agents were found to exist in mediating this event. The response to both agents is blocked by adrenergic antagonists and also by the protein synthesis inhibitor cycloheximide. Furthermore, cyclic AMP does not appear to be involved in mediating either angiotensin or noradrenaline stimulated fluid absorption. Since angiotensin is well known to release noradrenaline in other peripheral systems it seems possible that angiotensin-stimulated fluid transport is mediated via release of noradrenaline, since the angiotensin response was lost in animals pretreated with reserpine. The converse that noradrenaline enhances fluid absorption through the release of angiotensin has been eliminated since the response to noradrenaline is maintained in animals whose renal source of renin is removed by prior bilateral nephrectomy. Further support is lent to the proposal that the angiotensin action is mediated, by noradrenaline release' since it was found that in an in vitro intestinal preparation tyramine, an agent that releases endogenous noradrenaline, enhances net absorption of Na.
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Published date: 1979
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Local EPrints ID: 467242
URI: http://eprints.soton.ac.uk/id/eprint/467242
PURE UUID: 3b88b96d-036c-4609-bbd7-e0e94a6742da
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Date deposited: 05 Jul 2022 08:16
Last modified: 05 Jul 2022 08:16
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Author:
Christopher Paul Stewart
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