SODIUM METABOLISM IN IMMORTALIZED PROXIMAL TUBULE CELLS

在美国，高血压的发病率要高得多。 黑人比白人多。绝大多数的黑人高血压患者 属于盐敏型，可用 只有利尿剂。为了解释这种更高的发病率，一种“节俭基因” 已被假设为促进肾钠滞留，并导致 在高盐摄入量条件下，钠稳态发生改变。这个 这一提议的基本假设是存在不同的 个体近端肾小管钠重吸收的设定点 有节俭基因的人，要么在基线下，要么在激素调控下 条件。为了验证这一假设，人类近端肾小管细胞将 通过原代培养和永生化技术进行体外扩增 并在体外对这些细胞的钠代谢进行了研究。细胞内 钠浓度将用荧光探针SBFI测量 以及视频增强成像技术。钠代谢将是 通过测量激素对细胞内钠的影响来评价 主要钠离子的浓度和活性变化 转运体(Na，K-ATPase、Na/H交换器、Na-(HCO3)3共转运体)。 转运蛋白的活性将由钠的速率来确定 添加适当的抑制剂(哇巴因， EIPA，坐)。主要的荷尔蒙是血管紧张素II， 肾上腺素能药、利钠肽、甲状旁腺激素、缓激肽 和二十烷类化合物。评估近端肾小管的差异 存在可能与黑人高血压有关的特性，人类 材料最初将从两组中挑选：a)具有 有高血压家族史，以及b)无高血压的非高血压白人 家族性高血压的指征。为了进行分析， 钠参数之间将采用多元相关 体外测定的代谢和相关的临床或家族病史 与高血压有关的数据。初步实验将是 自发性肾小管近端小管细胞移植 高血压SHR和正常血压对照组WKY大鼠。

The incidence of essential hypertension is much greater in American blacks than in whites. The great majority of hypertension in blacks belongs to the salt-sensitive type which can be controlled with diuretics alone. To explain this greater incidence, a "thrifty gene" has been postulated which promotes renal sodium retention and results in altered sodium homeostasis under conditions of high salt intake. The underlying hypothesis for this proposal is the existence of a different set point for sodium reabsorption in the proximal tubule of individuals with the "thrifty gene", either under baseline or hormone-regulated conditions. To test this hypothesis, human proximal tubular cells will be expanded in-vitro by primary culture and immortalization techniques and the sodium metabolism of these cells probed in-vitro. Intracellular sodium concentrations will be measured with the fluorescent probe SBFI and video-enhanced imaging techniques. Sodium metabolism will be evaluated by measuring the influence of hormones on intracellular sodium concentrations and changes in the activity of the major sodium transporters (Na,K-ATPase, Na/H exchanger, Na-(HCO3)3 co-transporter). Transporter activity will be determined from rates of sodium concentration changes after addition of appropriate inhibitors (ouabain, EIPA, SITS). The major hormones of interest are angiotensin II, adrenergic agents, natriuretic peptide, parathyroid hormone, bradykinin and eicosanoids. To evaluate whether differences in proximal tubular properties exist that possibly pertain to hypertension in blacks, human material will initially be selected from two groups: a) blacks with a family history of hypertension, and b) non-hypertensive whites with no indication for hypertension in the family. For the analysis, multivariate correlation will be employed between parameters of sodium metabolism measured in-vitro and the relevant clinical or family history data pertaining to hypertension. Preliminary experiments will be carried out with renal proximal tubule cells from the spontaneously hypertensive SHR and the normotensive control WKY rats.