Sanada H, Jose P A, Hazen-Martin D, Yu P Y, Xu J, Bruns D E, Phipps J, Carey R M, Felder R A
University of Virginia Health Sciences Center, Charlottesville, VA, USA.
Hypertension. 1999 Apr;33(4):1036-42. doi: 10.1161/01.hyp.33.4.1036.
The ability of the dopamine-1 (D1)-like receptor to stimulate adenylyl cyclase (AC) and phospholipase C (PLC), inhibit sodium transport in the renal proximal tubule (RPT), and produce natriuresis is attenuated in several rat models of hypertension. Since the inhibitory effect of D1-like receptors on RPT sodium transport is also reduced in some patients with essential hypertension, we measured D1-like receptor coupling to AC and PLC in cultures of human RPT cells from normotensive (NT) and hypertensive (HT) subjects. Basal cAMP concentrations were the same in NT (n=6) and HT (n=4). However, the D1-like receptor agonist fenoldopam increased cAMP production to a greater extent in NT (maximum response=67+/-1%) than in HT (maximum response=17+/-5%), with a potency ratio of 105. Dopamine also increased cAMP production to a greater extent in NT (32+/-3%) than in HT (14+/-3%). The fenoldopam-mediated increase in cAMP production was blocked by SCH23390 (a D1-like receptor antagonist) and by antisense D1 oligonucleotides in both HT and NT, indicating action at the D1 receptor. The stimulatory effects of forskolin and parathyroid hormone-related protein of cAMP accumulation were not statistically different in NT and HT, indicating receptor specificity and an intact G-protein/AC pathway. The fenoldopam-stimulated PLC activity was not impaired in HT, and the primary sequence and expression of the D1 receptor were the same in NT and HT. However, D1 receptor serine phosphorylation in the basal state was greater in HT than in NT and was not responsive to fenoldopam stimulation in HT. These studies demonstrate the expression of D1 receptors in human RPT cells in culture. The uncoupling of the D1 receptor in both rats (previously described) and humans (described here) suggests that this mechanism may be involved in the pathogenesis of hypertension; the uncoupling may be due to ligand-independent phosphorylation of the D1 receptor in hypertension.
在几种高血压大鼠模型中，多巴胺 -1（D1）样受体刺激腺苷酸环化酶（AC）和磷脂酶C（PLC）、抑制肾近端小管（RPT）钠转运以及产生利钠作用的能力均减弱。由于在一些原发性高血压患者中，D1样受体对RPT钠转运的抑制作用也降低，我们检测了来自血压正常（NT）和高血压（HT）受试者的人RPT细胞培养物中D1样受体与AC和PLC的偶联情况。NT组（n = 6）和HT组（n = 4）的基础cAMP浓度相同。然而，D1样受体激动剂非诺多泮使NT组cAMP生成增加的程度（最大反应 = 67±1%）大于HT组（最大反应 = 17±5%），效价比为105。多巴胺使NT组cAMP生成增加的程度（32±3%）也大于HT组（14±3%）。在HT组和NT组中，非诺多泮介导的cAMP生成增加均被SCH23390（一种D1样受体拮抗剂）和反义D1寡核苷酸阻断，表明其作用于D1受体。在NT组和HT组中，福斯可林和甲状旁腺激素相关蛋白对cAMP积累的刺激作用无统计学差异，表明受体特异性和完整的G蛋白/AC途径。非诺多泮刺激的PLC活性在HT组中未受损，且NT组和HT组中D1受体的一级序列和表达相同。然而，基础状态下HT组中D1受体丝氨酸磷酸化程度高于NT组，且HT组中D1受体丝氨酸磷酸化对非诺多泮刺激无反应。这些研究证明了培养的人RPT细胞中D1受体的表达。大鼠（先前已描述）和人类（此处所述）中D1受体的解偶联表明，该机制可能参与高血压的发病机制；这种解偶联可能是由于高血压中D1受体的非配体依赖性磷酸化所致。
