Aiyar N, Nambi P, Crooke S T
Department of Molecular Pharmacology L521, Smith Kline & French Laboratories, King of Prussia, PA 19406-0939.
Cell Signal. 1990;2(2):153-60. doi: 10.1016/0898-6568(90)90018-6.
Desensitization of vasopressin V2 receptor-mediated adenylate cyclase was studied in canine kidney cell line, MDCK cells. Overnight treatment of MDCK cells with arginine vasopressin (AVP) resulted in a loss of vasopressin receptors and an inhibition of cAMP accumulation in response to AVP. Both the loss of receptor and reduction in cAMP accumulation were time- and AVP concentration-dependent. Desensitization was selective for AVP because cAMP formation in response to isoproterenol, prostaglandin E1 (PGE1) and forskolin was not affected by AVP pre-treatment. Pre-treatment of MDCK cells with phorbol dibutyrate (PDBu) also caused a dose-dependent inhibition of AVP mediated cAMP accumulation, but not of isoproterenol-, PGE1- and forskolin-induced cAMP accumulation. PDBu pre-treatment did not cause loss of vasopressin receptors. Instead, the affinity for vasopressin was changed by PDBu treatment. Pre-treatment of the cells with pertussis toxin (PT) had no effect on the desensitization and downregulation of vasopressin (V2) receptors, suggesting that the desensitization may not be mediated by pertussis toxin sensitive G-protein. Our data suggest that pre-treatment of MDCK cells with AVP or PDBu caused desensitization of AVP-mediated cAMP accumulation and that downregulation of V2 receptors required agonist occupancy of the receptors, whereas the affinity of the receptors was changed by phorbol ester treatment.
在犬肾细胞系MDCK细胞中研究了血管加压素V2受体介导的腺苷酸环化酶脱敏作用。用精氨酸血管加压素（AVP）对MDCK细胞进行过夜处理，导致血管加压素受体丧失以及对AVP刺激的cAMP积累的抑制。受体丧失和cAMP积累减少均呈时间和AVP浓度依赖性。脱敏作用对AVP具有选择性，因为对异丙肾上腺素、前列腺素E1（PGE1）和福斯高林的cAMP形成不受AVP预处理的影响。用佛波醇二丁酸酯（PDBu）预处理MDCK细胞也导致AVP介导的cAMP积累呈剂量依赖性抑制，但对异丙肾上腺素、PGE1和福斯高林诱导的cAMP积累无影响。PDBu预处理未导致血管加压素受体丧失。相反，PDBu处理改变了对血管加压素的亲和力。用百日咳毒素（PT）预处理细胞对血管加压素（V2）受体的脱敏和下调没有影响，这表明脱敏可能不是由百日咳毒素敏感的G蛋白介导的。我们的数据表明，用AVP或PDBu预处理MDCK细胞会导致AVP介导的cAMP积累脱敏，V2受体的下调需要激动剂占据受体，而佛波酯处理会改变受体的亲和力。
