Premium
PROFILE OF A NEW PRAZOSIN CONGENER, BL‐5111A. STUDIES IN THE RAT
Author(s) -
Oates Helen F.,
Stoker Lynette M.,
Stokes G. S.
Publication year - 1979
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.1440-1681.1979.tb00725.x
Subject(s) - prazosin , phentolamine , blood pressure , vasodilation , heart rate , endocrinology , pharmacology , chemistry , medicine , propranolol , antagonist , receptor
SUMMARY 1. The effects on blood pressure and heart rate of prazosin and a structurally‐related congener, BL‐5111A, were compared in conscious and anaesthetized rats. 2. Both agents induced dose‐related falls in systolic and diastolic blood pressure, with relatively little effect on heart rate. The hypotensive potency of prazosin was twenty‐fold greater than that of BL‐5111A. 3. The hypotensive activity of prazosin was abolished by pretreatment with the ganglionic blocking agent, pentolinium, or the α‐adrenoceptor blocking agent, phentolamine, whereas BL‐5111A retained significant hypotensive activity (up to 28%) after either pretreatment. 4. Both prazosin and BL‐5111A attenuated pressor responses to noradrenaline, and reversed the responses to adrenaline, prazosin being, in this respect, 6 times more potent than BL‐5111 A. There was a highly significant relationship between the α‐adrenoceptor blocking activity of either agent and its hypotensive effect. 5. BL‐5111A differed from prazosin in possessing, in addition to its predominant α‐adrenoceptor blocking action, a minor component of action attributable to direct vasodilatation.