ION TRANSPORT & ITS REGULATION IN PROXIMAL RENAL TUBULES

离子输运机制及其几种修饰 将用电生理技术研究神经递质 分离的兔近端小管灌流节段(S1、S2、S3)。 实验的目的是1)确定根尖的被动特性 和基侧膜和细胞旁途径) 跨上皮阻力，b)心尖部与基底外侧的表观比率 膜电阻，以及c)细胞膜电位。这些数据将 允许我们计算等效电阻和 细胞膜的电动势。离子取代将是 用于测定电池的离子扩散渗透率 膜。2)研究去甲肾上腺素、多巴胺、 乙酰胆碱和其他改善体液重吸收的物质 细胞膜的被动性质。3)确定系统的稳态 离子敏感法测定细胞内Na、K和C_1的活性 用于确定上坡和下坡运输过程的微电极 确定在给定膜上的被动离子传输是否可以 电扩散。如果这些实验成功，细胞内离子 活度测量将被应用于研究 神经递质的作用，它改变液体的运输。这些 实验应该对近端肾小管有更好的理解 肾脏整体的功能和体液转运的调节。

The mechanism of ion transport and their modifications by several neurotransmitters will be studied with electrophysiological techniques in isolated perfused segments (S1, S2, S3) of rabbit proximal tubules. Experiments are designed 1) to determine the passive properties of apical and basolateral membranes and paracellular pathway by measuring a) transepithelial resistance, b) apparent ratio of apical to basolateral membrane resistance, and c) cell membrane potentials. These data will allow us to calculate the equivalent electrical resistances and electromotive forces of the cell membranes. Ionic substitutions will be used to determine the ionic diffusional permeability of the cell membranes. 2) To study the effects of norepinephrine, dopamine, acetylocholine and other substances which modify fluid reabsorption on the passive properties of the cell membranes. 3) To determine the steady-state intracellular activities of Na, K and C1, by using ion-sensitive microelectrodes to define uphill and downhill transport process and to ascertain whether passive ion transport at a given membrane can be electrodiffusional. If these experiments are successful, intracellular ion activity measurements will be applied to the study of the mechanism of action of neurotransmitters which modify fluid transport. These experiments should provide a better understanding of proximal tubular function and of the regulation of fluid transport by the kidney as a whole.