Document Detail

Effect of chronic ETA-selective endothelin receptor antagonism on blood pressure in experimental and genetic hypertension in rats.
MedLine Citation:
PMID:  9222550     Owner:  NLM     Status:  MEDLINE    
1. Chronic treatment with a combined ETA/ETB endothelin receptor antagonist has been shown to reduce blood pressure in experimental rat models of hypertension in which endothelin-1 gene overexpression occurs in the walls of blood vessels, particularly small, resistance-sized arteries, but not in those genetic or experimental models of hypertension in which there is no overexpression of vascular endothelin-1. Failure of some experimental models of hypertension to respond to treatment with the combined ETA/ETB endothelin antagonist may be due in part to blockade of vasorelaxant endothelial ETB receptors which could in theory reduce the efficacy of endothelin antagonism. 2. In this study the orally active ETA-selective endothelin antagonists A-127722.5 and LU 135252 were used in chronic experiments on deoxycorticosterone acetate (DOCA)-salt hypertensive rats (which overexpress vascular endothelin-1 and respond with blood pressure lowering to combined ETA/ETB endothelin receptor antagonism), on spontaneously hypertensive rats (SHR) (which do not overexpress vascular endothelin-1 and do not respond with blood pressure lowering to the combined ETA/ETB receptor antagonist), and in 1-kidney 1 clip Goldblatt (1-K IC) hypertensive rats (which present mild overexpression of vascular endothelin-1 but do not respond with blood pressure lowering to the combined ETA/ETB receptor antagonist). Additionally, it has been suggested that interruption of the renin-angiotensin system may sensitize responses to endothelin antagonism. Accordingly, SHR were treated with an angiotensin converting enzyme inhibitor, cilazapril, in addition to the ETA receptor antagonist. 3. Blood pressure of DOCA-salt hypertensive rats was lowered by a mean of 24 and of 27 mmHg (P < 0.01) by A-127722.5 after 4 weeks of treatment, when given orally at two different doses (10 and 30 mg kg-1 day-1), and by 18 mmHg by LU 135252 50 mg kg-1 day-1. 4. SHR treated with A-127722.5 for 8 weeks starting at 12 weeks of age exhibited the same progressive rise in blood pressure as untreated SHR. Addition of cilazapril resulted in similar reduction of blood pressure in A-127722.5-treated and untreated SHR. 5. Treatment of 1-K IC hypertensive rats with the dose of LU 135252 which lowered blood pressure in DOCA-salt hypertensive rats did not cause any reduction in blood pressure relative to untreated rats. 6. These results demonstrate that treatment with either dose of the selective ETA receptor antagonists A-127722.5 or LU 135252 caused reductions in blood pressure similar to those obtained for a combined ETA/ETB endothelin antagonist. Blood pressure was lowered only in hypertensive rats known to overexpress vascular endothelin-1 (DOCA-salt hypertensive rats) but not in those which do not (SHR) or only have mild vascular overexpression of endothelin-1 gene (1-K 1C hypertensive rats). Reduction in activity of the renin-angiotensin system in SHR did not sensitize blood pressure to potential hypotensive effects of an ETA-selective receptor antagonist.
E L Schiffrin; A Turgeon; L Y Deng
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  British journal of pharmacology     Volume:  121     ISSN:  0007-1188     ISO Abbreviation:  Br. J. Pharmacol.     Publication Date:  1997 Jul 
Date Detail:
Created Date:  1997-09-15     Completed Date:  1997-09-15     Revised Date:  2008-11-20    
Medline Journal Info:
Nlm Unique ID:  7502536     Medline TA:  Br J Pharmacol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  935-40     Citation Subset:  IM    
MRC Multidisciplinary Research Group on Hypertension, Clinical Research Institute of Montréal, University of Montréal, Québec, Canada.
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MeSH Terms
Antihypertensive Agents / pharmacology*
Blood Pressure / drug effects*
Dose-Response Relationship, Drug
Endothelins / blood
Hemodynamics / drug effects
Hypertension / chemically induced,  genetics,  physiopathology*
Hypertension, Renovascular / physiopathology
Phenylpropionates / pharmacology
Pyrimidines / pharmacology
Pyrrolidines / pharmacology
Rats, Inbred SHR
Rats, Sprague-Dawley
Receptors, Endothelin / antagonists & inhibitors*
Renin / blood
Reg. No./Substance:
0/A 127722; 0/Antihypertensive Agents; 0/Endothelins; 0/LU 135252; 0/Phenylpropionates; 0/Pyrimidines; 0/Pyrrolidines; 0/Receptors, Endothelin; 64-85-7/Desoxycorticosterone; EC

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