Alpha-adrenoceptor antagonistic effects and antihypertensive activity of SGB-1534 in conscious normotensive and deoxycorticosterone acetate (DOCA)-salt hypertensive dogs: comparison with prazosin.
In conscious normotensive and deoxycorticosterone acetate (DOCA)-salt hypertensive dogs, alpha-adrenoceptor antagonistic and antihypertensive actions of SGB-1534, given orally, were compared with those of prazosin. SGB-1534 and prazosin did not markedly influence systemic blood pressure (SBP) and heart rate (HR) in normotensive dogs. These alpha 1-adrenoceptor antagonists inhibited SBP and HR increases induced by i.v. adrenaline in a dose-dependent manner. In DOCA-salt hypertensive dogs, persistent hypotension, accompanied by a reflex tachycardia, occurred after oral administration of SGB-1534 and prazosin. The hypotensive activity of SGB-1534 was much more potent in magnitude and duration than that of prazosin. In isolated canine mesenteric and femoral arteries, SGB-1534, compared to prazosin, elicited a more potent inhibition on the contractile response to a relatively selective alpha 1-adrenoceptor agonist, phenylephrine. It appears that the antihypertensive activity of SGB-1534, like prazosin, is nearly in parallel with its alpha 1-adrenoceptor antagonistic effect.
Haruta
K
K
Department of Pharmacology, Fujigotemba Research Laboratories, Chugai Pharmaceutical Co., Ltd., Shizuoka, Japan.
Baba
A
A
Akima
M
M
Koga
T
T
Shiraki
Y
Y
Sakai
K
K
D000317:Adrenergic alpha-Antagonists; D000818:Animals; D000959:Antihypertensive Agents; D001794:Blood Pressure / Q000187:drug effects; D003900:Desoxycorticosterone; D004285:Dogs; D005260:Female; D005263:Femoral Artery / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D010656:Phenylephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology*; D011799:Quinazolines / Q000494:pharmacology*
D000317:Adrenergic alpha-Antagonists; D000959:Antihypertensive Agents; D011799:Quinazolines; D010656:Phenylephrine; D003900:Desoxycorticosterone; C042712:SGB 1534; D011224:Prazosin