Sabouni M H, Cushing D J, Mustafa S J
Department of Pharmacology, School of Medicine, East Carolina University, Greenville, North Carolina.
J Pharmacol Exp Ther. 1989 Dec;251(3):943-8.
The involvement of a guanine-nucleotide-binding regulatory protein (G protein) in the relaxing responses to adenosine receptor agonists was investigated in bovine coronary vessels. Ring segments of left anterior descending artery branches were suspended in organ baths for measurement of isometric tension. The adenosine analogs, 5'-N-ethylcarboxamidoadenosine (NECA) and 2-chloroadenosine (CAD) caused concentration-dependent relaxations of coronary rings contracted with KCl. The relaxing effects of NECA and CAD were antagonized by the adenosine receptor antagonist 8-phenyltheophylline indicating the involvement of an adenosine receptor. In a separate series of experiments, incubation with cholera toxin inhibited the relaxing responses to NECA, CAD and isoproterenol but not those produced by sodium nitroprusside. Treatment with forskolin did not reduce the relaxing responses to NECA or CAD. N-ethylmaleimide and NaF/AlCl3 caused significant inhibition of the relaxations produced by both NECA and CAD. Incubation with pertussis toxin was without effect on relaxations induced by NECA and CAD. These results provide evidence for the involvement of G protein (possibly stimulatory G proteins) in the relaxing effects mediated by the bovine coronary artery adenosine receptor.
在牛冠状动脉中研究了鸟嘌呤核苷酸结合调节蛋白（G蛋白）参与对腺苷受体激动剂的舒张反应。将左前降支动脉分支的环段悬挂于器官浴槽中以测量等长张力。腺苷类似物5'-N-乙基羧酰胺腺苷（NECA）和2-氯腺苷（CAD）引起氯化钾预收缩的冠状动脉环浓度依赖性舒张。腺苷受体拮抗剂8-苯基茶碱可拮抗NECA和CAD的舒张作用，提示腺苷受体参与其中。在另一系列实验中，用霍乱毒素孵育可抑制对NECA、CAD和异丙肾上腺素的舒张反应，但不影响硝普钠产生的舒张反应。用福斯高林处理并未降低对NECA或CAD的舒张反应。N-乙基马来酰亚胺和NaF/AlCl3可显著抑制NECA和CAD产生的舒张反应。用百日咳毒素孵育对NECA和CAD诱导的舒张反应无影响。这些结果为G蛋白（可能是刺激性G蛋白）参与牛冠状动脉腺苷受体介导的舒张作用提供了证据。
