Document Detail

Pinacidil-induced relaxation in pulmonary arteries isolated from pulmonary hypertensive and normotensive rats and pre-contracted with different spasmogens.
MedLine Citation:
PMID:  7549228     Owner:  NLM     Status:  MEDLINE    
Vasorelaxant responses to the potassium channel opening drug, pinacidil, were obtained on preparations of pulmonary artery and aorta taken from rats with pulmonary hypertension (induced by chronic hypoxia or monocrotaline) and pre-contracted either submaximally with endothelin-1 (ET-1), PGF2 alpha, U46619 (thromboxane-mimetic) or noradrenaline (NA), or with 80 mM K+. In pulmonary artery, but not aorta, from pulmonary hypertensive rats the maximum relaxant response to pinacidil was increased, when compared with data in control rats, irrespective of the spasmogen used to precontract the tissues. The increase in maximum was associated with relaxation to below the tissue resting baseline and probably reflected the presence of inherent contractile tone in arteries from pulmonary hypertensive rats. In addition the potency (-log EC50) of pinacidil was increased in pulmonary arteries from pulmonary hypertensive rats but this was seen only in preparations contracted with ET-1 (30-fold increase) or NA (seven-fold increase) and not in those contracted with PGF2 alpha, U46619 or K+. As a result, in ET-1 contracted preparations from pulmonary hypertensive rats pinacidil was 29-fold more potent on pulmonary artery than on aorta. To explain the increase in potency it is speculated that during the development of pulmonary hypertension the mechanism whereby ET-1 and NA contract pulmonary arteries may change from one in which Ca2+ influx plays only a minor role to one in which Ca2+ influx predominates, although no direct evidence to support this speculation has yet been obtained.
J C Wanstall; C S Kay; S R O'Donnell
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Pulmonary pharmacology     Volume:  7     ISSN:  0952-0600     ISO Abbreviation:  Pulm Pharmacol     Publication Date:  1994 Dec 
Date Detail:
Created Date:  1995-11-20     Completed Date:  1995-11-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9007551     Medline TA:  Pulm Pharmacol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  401-8     Citation Subset:  IM    
Department of Physiology and Pharmacology, University of Queensland, Brisbane, Australia.
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MeSH Terms
Anoxia / physiopathology
Antihypertensive Agents / pharmacology*
Aorta, Thoracic / drug effects
Guanidines / pharmacology*
Hypertension, Pulmonary / chemically induced,  physiopathology*
Muscle Contraction / drug effects
Muscle Relaxation / drug effects
Muscle, Smooth, Vascular / drug effects*
Pulmonary Artery / drug effects*
Rats, Wistar
Vasoconstrictor Agents / pharmacology
Reg. No./Substance:
0/Antihypertensive Agents; 0/Guanidines; 0/Vasoconstrictor Agents; 315-22-0/Monocrotaline; 85371-64-8/Pinacidil

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

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