[The hypotensive effects and mechanism of SGB-483, a newly-synthesized hypotensive agent].
The effects of SGB-483, a newly-synthesized hypotensive agent, on the blood pressure were studied in unanesthetized and anesthetized rats. SGB-483 produced a significant hypotensive action in the conscious SHR and renal hypertensive (clipping) rats, and it caused reversal of the pressor response to adrenaline in the anesthetized Wistar-Imamichi rats, SHR, and clipping rats. In an isolated guinea pig aorta preparation, SGB-483 competitively inhibited the contractile response to phenylephrine with a pA2 value of 7.64 +/- 0.08. In pithed rats that were pretreated with beta-adrenoceptor blocker, the pressor effect of adrenaline (1 microgram/kg) was not completely blocked by either prazosin (1 mg/kg), an alpha 1-selective blocker, or yohimbine (1 mg/kg), an alpha 2-selective blocker. SGB-483 (1 mg/kg) had no effects on the prazosin-resistant part of the pressor effect of adrenaline, but significantly inhibited the yohimbine-resistant part. Clonidine-induced reversal of the tachycardia induced in the pithed rat by cardiac sympathetic nerve stimulation was unaffected by SGB-483, indicating that SGB-483 is a selective antagonist of the alpha 1-adrenoceptor.
D000317:Adrenergic alpha-Antagonists; D000758:Anesthesia; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D003243:Consciousness; D003655:Decerebrate State; D006168:Guinea Pigs; D006973:Hypertension / Q000188:drug therapy; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
D000317:Adrenergic alpha-Antagonists; D000959:Antihypertensive Agents; D010879:Piperazines; C035927:SGB 483