Studies on the mechanism of action of angiotenson
Studies on the mechanism of action of angiotenson
A study has been made of the effects of angiotensin on fluid transport by rat intestine in-+vivo. The hormone was shown to exert a dose dependant dual action on fluid transport by the intestine, low subpreasor infusions stimulate jejunal and colonic transport whilst high pressor infusions inhibit transfer.Both the stimulation and the inhibition are unaccompanied by changes in potential difference, short circuit current or tranmwral resistance. This supports the view that angiotensin exerts its action through alectroneutral transport processes. A study of the time course of the two responses indicated that the inhibition had a very long half life in direct contrast to the stimulation which had a rapid induction and decay. The structural activity requirements for angiotensin action on intestinal fluid transport were compared with the press or, nprotropic and the thirstand salt appetite stimulating actions of the hormone. Thanylalanine inposition eight of the molecule is important for the intrinsic activity on pressor, motropic and thirst systems. Aliphatic substitutions in this position produce antagonists with very low activity. In contrast, substitutions can be made for phenylalan ne without affecting the fluid stimulating activity of the molecule. Angiotensin releases noradranaline from sympathetic nerve endings and furthermore the structural requirements for these two actions of the hormone are similar. The hypothesis that angiotensin acts in the intestine via the mediation of noradrenaline was investigated. Preliminary experiments indicated that there are Similarities between the effects of noradrenaline and angiotensin on jejunal transport. Both compounds affect transport in a dose related manner. The stimulation produced by both compounds could be inhibited by the acadrenergic antagonist phentolamine and cyolohsadmide. These results are consistent with the view that angiotensin may act via the release of noradrenalina.
University of Southampton
1977
Levens, Nigel
(1977)
Studies on the mechanism of action of angiotenson.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
A study has been made of the effects of angiotensin on fluid transport by rat intestine in-+vivo. The hormone was shown to exert a dose dependant dual action on fluid transport by the intestine, low subpreasor infusions stimulate jejunal and colonic transport whilst high pressor infusions inhibit transfer.Both the stimulation and the inhibition are unaccompanied by changes in potential difference, short circuit current or tranmwral resistance. This supports the view that angiotensin exerts its action through alectroneutral transport processes. A study of the time course of the two responses indicated that the inhibition had a very long half life in direct contrast to the stimulation which had a rapid induction and decay. The structural activity requirements for angiotensin action on intestinal fluid transport were compared with the press or, nprotropic and the thirstand salt appetite stimulating actions of the hormone. Thanylalanine inposition eight of the molecule is important for the intrinsic activity on pressor, motropic and thirst systems. Aliphatic substitutions in this position produce antagonists with very low activity. In contrast, substitutions can be made for phenylalan ne without affecting the fluid stimulating activity of the molecule. Angiotensin releases noradranaline from sympathetic nerve endings and furthermore the structural requirements for these two actions of the hormone are similar. The hypothesis that angiotensin acts in the intestine via the mediation of noradrenaline was investigated. Preliminary experiments indicated that there are Similarities between the effects of noradrenaline and angiotensin on jejunal transport. Both compounds affect transport in a dose related manner. The stimulation produced by both compounds could be inhibited by the acadrenergic antagonist phentolamine and cyolohsadmide. These results are consistent with the view that angiotensin may act via the release of noradrenalina.
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Published date: 1977
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Local EPrints ID: 467251
URI: http://eprints.soton.ac.uk/id/eprint/467251
PURE UUID: 21b5e7ea-6925-4f03-8431-00cd25a03f6e
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Date deposited: 05 Jul 2022 08:16
Last modified: 05 Jul 2022 08:16
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Author:
Nigel Levens
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