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AN IN VITRO STUDY OF INTERACTIONS BETWEEN DOXAZOSIN AND ENALAPRILAT AT VASCULAR α 1 ‐ADRENOCEPTORS
Author(s) -
Tierney Garth,
Marwood John,
Stokes Gordon
Publication year - 1989
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1989.tb01567.x
Subject(s) - enalaprilat , doxazosin , phenylephrine , antagonist , medicine , endocrinology , agonist , angiotensin ii , chemistry , angiotensin converting enzyme , vascular smooth muscle , methoxamine , ace inhibitor , pharmacology , receptor , biology , smooth muscle , blood pressure
SUMMARY 1. Isolated perfused male Sprague‐Dawley rat tail artery segments were used to investigate interactions between the α‐ 1 ‐adrenoceptor antagonist, doxazosin, and the angiotensin converting enzyme (ACE) inhibitor, enalaprilat, using phenylephrine (PE) as the α 1 ‐adrenoceptor agonist. 2. In concentrations of up to 10– 5 mol/L, enalaprilat had no effect on arterial responses to PE. 3. Doxazosin produced a concentration‐dependent competitive α 1 ‐adrenoceptor antagonism, yielding a mean p A 2 value of 8.72. 4. In the continuous presence of 10 −6 mol/L enalaprilat, doxazosin with a p A 2 value of 9.10 was a 2.4‐fold more potent α 1 ‐adrenoceptor antagonist than in the absence of enalaprilat. 5. These results are interpreted to indicate that endogenously produced angiotensin II can modulate the activity of α 1 ‐adrenoceptors in vascular smooth muscle.