Yasunari K, Kohno M, Murakawa K, Yokokawa K, Horio T, Takeda T
First Department of Internal Medicine, Osaka City University Medical School, Japan.
Am J Physiol. 1993 Jan;264(1 Pt 2):F24-30. doi: 10.1152/ajprenal.1993.264.1.F24.
The interaction between dopamine DA1 receptors and a phorbol ester was studied to elucidate the role of protein kinase C in the response of this receptor. The in vitro binding of [3H]Sch 23390 to DA1 receptor sites on vascular smooth muscle cells was saturable. The extent of [3H]Sch 23390 binding to phorbol ester-treated cells was increased without any change in the dissociation constant. The production of adenosine 3',5'-cyclic monophosphate (cAMP) in response to DA1 receptor stimulation was enhanced by preincubation of vascular smooth muscle cells with the phorbol ester for 4 h. However, no enhancement was observed when the medium used for preincubation was supplemented with a protein kinase C inhibitor. Direct stimulation of stimulatory guanine nucleotide-binding regulatory protein with 5-guanylylimidodiphosphate and direct stimulation of adenylate cyclase with forskolin produced no significant differences in cyclase levels between phorbol ester-treated and untreated cells. These results suggest that activation of protein kinase C triggers an increase in the membrane expression of DA1 receptors, thereby enhancing receptor-coupled cAMP generation.
研究了多巴胺DA1受体与佛波酯之间的相互作用，以阐明蛋白激酶C在该受体反应中的作用。[3H]Sch 23390与血管平滑肌细胞上DA1受体位点的体外结合具有饱和性。[3H]Sch 23390与佛波酯处理细胞的结合程度增加，而解离常数没有任何变化。用佛波酯对血管平滑肌细胞预孵育4小时，可增强对DA1受体刺激的3',5'-环磷酸腺苷（cAMP）生成。然而，当预孵育所用培养基中添加蛋白激酶C抑制剂时，未观察到增强作用。用5-鸟苷酰亚胺二磷酸直接刺激刺激性鸟嘌呤核苷酸结合调节蛋白，并用福斯可林直接刺激腺苷酸环化酶，在佛波酯处理和未处理的细胞之间，环化酶水平没有显著差异。这些结果表明，蛋白激酶C的激活触发了DA1受体膜表达的增加，从而增强了受体偶联的cAMP生成。
