Separovic D, Kester M, Haxhiu M A, Ernsberger P
Department of Medicine, Case Western Reserve School of Medicine, Cleveland, OH 44106-4982, USA.
Brain Res. 1997 Feb 28;749(2):335-9. doi: 10.1016/S0006-8993(96)01372-8.
The I1-imidazoline receptor is expressed in the rostral ventrolateral medulla (RVLM) where it mediates vasodepression, and in PC12 pheochromocytoma cells where it elicits generation of diacylglycerol independent of phosphatidylinositol turnover or activation of phospholipase D. We hypothesized that the I1-imidazoline receptor couples to a phosphatidylcholine-selective phospholipase C (PC-PLC). The I1-agonist moxonidine elicited diacyglyceride accumulation and release of [3H]phosphocholine from PC12 cells prelabeled with [3H]choline. The PC-PLC inhibitor D609 abolished both responses. Microinjection of D609 into the RVLM of hypertensive rats blocked the vasodepressor response to intravenous moxonidine. These data implicate PC-PLC in cellular and organismic responses to I1-receptor stimulation.
I1-咪唑啉受体在延髓头端腹外侧区（RVLM）表达，在该区域它介导血管舒张抑制；它也在PC12嗜铬细胞瘤细胞中表达，在这些细胞中它引发二酰甘油的生成，且该过程不依赖磷脂酰肌醇周转或磷脂酶D的激活。我们推测I1-咪唑啉受体与磷脂酰胆碱选择性磷脂酶C（PC-PLC）偶联。I1-激动剂莫索尼定可引起用[3H]胆碱预标记的PC12细胞中二酰甘油积累和[3H]磷酸胆碱释放。PC-PLC抑制剂D609消除了这两种反应。向高血压大鼠的RVLM微量注射D609可阻断静脉注射莫索尼定引起的血管舒张反应。这些数据表明PC-PLC参与了细胞和机体对I1-受体刺激的反应。
