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Cellular mechanisms of hormone and drug interaction in ion transport in the nephron

肾单位离子转运中激素和药物相互作用的细胞机制

基本信息

批准号：
10470027
负责人：
IMAI Masashi
金额：
$ 4.22万
依托单位：
Jichi Medical School
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

(1) Renal tubular action of CS-045(troglitazone): CS-045 has been developed for the treatment of insulin resistant diabetes mellitus. The mechanism of action is assumed to be sensitization of insulin receptor rather than stimulation of insulin release. To elucidate the mechanisms by which this agent causes edema as a side-effect, we examined direct action of CS-045 on the rabbit proximal straight tubule (PST) perfused in vitro. By measuring the electrophysiological parameters representing HCOィイD23ィエD2-conductance in the basolateral membrane and Na-3HC0ィイD23ィエD2 co-transporter activity as determined by changes in intracellular pH(pHi), we demonstrated that CS-045 directly stimulates Na-3HC0ィイD23ィエD2 co-transporter activity in the basolateral membrane in a dose-dependent manner, leading to an increase in Na reabsorption in the PST. This would, at least in part, be responsible for edema caused by CS-045.(2) Renal tubular function of receptor/transporter knockout mice: We established clearance technique to examine renal function of PGE2-knockout mice. In mice anesthetized with pentobarbital, constant iv infusion was performed from tail vein. Urine volume, osmolality and Na were measured on samples collected from the bladder. PGE2 caused significant increase in urine volume and Na excretion in he control mice, but not in the PGE2-recptor knockout mice. We succeeded to perfuse isolated PST from the kidney of P-glycoprotein (P-gp) knockout mice. From the decrement of intracellular rodamin fluorescence, transport activity of P-gp was estimated It was shown that P-gp is critical for drug excretion from the apical membrane of PST by acting through mechanisms linking with activation of PKC and P1-3 kinase in the control mice, but that P-gp knockout mice lack this function.

(1) CS-045（曲格列酮）的肾小管作用：CS-045已被开发用于治疗胰岛素抵抗型糖尿病。其作用机制被认为是胰岛素受体的致敏作用，而不是刺激胰岛素释放。为了阐明该药物引起水肿的副作用机制，我们研究了CS-045对体外灌注的兔近端直小管（PST）的直接作用。通过测量电生理参数代表HCOィイc15ィエD2-conductance基底膜和Na-3HC0ィイc15ィエD2 co-transporter活动由细胞内的pH值的变化(φ),我们证明了cs - 045直接刺激Na-3HC0ィイc15ィエD2 co-transporter活动基底外侧膜剂量依赖性的方式,导致在PST钠重吸收增加。这至少是CS-045造成水肿的部分原因。(2)受体/转运蛋白敲除小鼠的肾小管功能：我们建立了清除技术来检测pge2敲除小鼠的肾功能。戊巴比妥麻醉小鼠，从尾静脉持续静脉输注。测定膀胱标本的尿量、渗透压和钠浓度。PGE2引起对照组小鼠尿量和钠排泄量显著增加，而PGE2受体敲除小鼠无显著增加。我们成功地从p -糖蛋白（P-gp）敲除小鼠的肾脏中灌注分离的PST。通过细胞内罗丹明荧光的减弱，估计了P-gp的运输活性。结果表明，P-gp通过与对照小鼠PKC和P1-3激酶激活相关的机制对PST根尖膜的药物排泄至关重要，但P-gp敲除小鼠缺乏这种功能。