Document Detail

Magnesium-neurohypophyseal hormone interactions in contraction of vascular smooth muscle.
MedLine Citation:
PMID:  1130565     Owner:  NLM     Status:  MEDLINE    
The contractile responses of helically cut rat aortic strips to neurohypophyseal hormones and synthetic analogues in the presence and absence of 1.2 mM external magnesium ions [Mg++]o was studied. These experiments demonstrate that 1) [Mg++]o potentiates the contractile actions of a variety of neurohypophyseal peptides on vascular smooth muscle. 2) [Mg++]o can alter both the ED50s (i.e., hormone-receptor affinities) and intrinsic activities (or maximum contractile responses) of these molecules on vascular muscle. 3) The amino acid moieties in positions 1, 2, 3, and 8 of the vasopressin molecule interact, differentially, with [Mg++] to produce contraction of vascular muscle. 4) The length of the side chain, and basicity, in position 8 of the vasopressin molecule are probably important in Mg potentiation in mammalian vascular muscle. 5) Interaction of Mg with an aromatic group in position 3 might be critical for potency of vasopressin hormones of mammalian vascular muscle; the ED50 for oxytocin is not shifted to lower concentrations in the presence of [Mg++]o. Collectively, these data suggest that Mg probably acts at more than one site in vascular smooth muscle in the production of neurohypophyseal peptide-activated contractions. In addition, the present findings indicate that the Mg dependence of these peptides on at least one vascular muscle, rat aorta, is a direct function of the rat pressor potency of the molecules.
B M Altura
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  228     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1975 May 
Date Detail:
Created Date:  1975-08-08     Completed Date:  1975-08-08     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1615-20     Citation Subset:  IM    
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MeSH Terms
Aorta, Thoracic / drug effects
Arginine Vasopressin / pharmacology
Binding Sites
Deamino Arginine Vasopressin / pharmacology
Drug Synergism
Lypressin / pharmacology
Magnesium / pharmacology*
Muscle Contraction / drug effects*
Muscle, Smooth / drug effects
Oxytocin / pharmacology
Receptors, Drug
Structure-Activity Relationship
Vasomotor System / drug effects*
Vasopressins / analogs & derivatives,  pharmacology*
Reg. No./Substance:
0/Receptors, Drug; 11000-17-2/Vasopressins; 113-79-1/Arginine Vasopressin; 16679-58-6/Deamino Arginine Vasopressin; 50-56-6/Oxytocin; 50-57-7/Lypressin; 7439-95-4/Magnesium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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