- 作者: C.H. Chen; K.S. Lin; S.H.H. Chan
- 作者服務機構: Institute of Pharmacology; National Yang-Ming Medical College, Taipei, Taiwan, ROC
- 中文摘要: --
- 英文摘要: In adult male Sprague-Dawley rats anesthetized with pentobarbital sodium, we elucidated the molecular consequence of central α2-adrenoceptor activation. The hypotensive and negative chronotropic and isotropic actions of the α2-adreno- ceptor agonist guanabenz were used as our experimental index. Intracerebro- ventricular administration of pertussis toxin (2.5 μg) significantly attenuated the cardiovascular suppressant effects of the aminoguanidine compound(100 μg/kg i.v.). However, application of N-ethylmaleimide (0.125 or 0.250 μg), phorbol 12- myristate 13一acetate(1.25 or 2.50 μg), cholera toxin(1.25 or 2.50 μg) or forsko- lin (12.5 or 25.0 μg) into the lateral cerebral ventricle elicited no appreciable blunting effect on the circulatory depression produced by guanabenz. These results were essentially duplicated when pertussis toxin (0.125 or 0.250 μg), N- ethylmaleimide (0.0125 or 0.05 μg), phorbol 12-myristate 13-acetate (0.125 or 0.25 μg), cholera toxin (0.125 or 0.25 μg) or forskolin(1.25 or 2.50μg)was microinjected bilaterally to the nucleus reticularis gigantocellularis, a medullary site believed to be intimately related to the antihypertensive action of guanabenz. These findings suggest that stimulation of the α2- adrenoceptors in the medulla oblongata may result in the activation of a pertussis toxin-sensitive GTP-binding regulatory protein. They further suggest that the biologic signals subsequent to this action may not be linked to Gs, Gi or Gp but possibly Go.
- 中文關鍵字: --
- 英文關鍵字: Central az adrenoceptor; Guanabenz; Nucleus reticularis gigantocellularis; GTP-binding regulatory proteins; Pertussis toxin