Stanton B A, Giebisch G H
Am J Physiol. 1982 Nov;243(5):F487-93. doi: 10.1152/ajprenal.1982.243.5.F487.
Microperfusion studies were performed on superficial distal tubules to determine the relationship between potassium secretion by the distal tubule and plasma potassium concentrations in rats on a control and a high potassium diet. Potassium was infused in graded doses into animals on a control diet and into animals receiving a high potassium diet. Since potassium loading in rats is known to inhibit proximal tubular sodium and fluid reabsorption and thereby could lead to nonspecific flow-related stimulation of potassium secretion by the distal tubule, continuous microperfusion techniques at constant flow rate were used to measure the rate of potassium secretion. Additionally, plasma aldosterone levels were measured and renal clearance experiments carried out. The results show that potassium secretion, restricted to cells of the late distal tubule, reaches a maximal rate at a plasma potassium concentration of about 6 meq/liter. Potassium adaptation significantly enhances potassium secretion compared with animals on a control diet over a range of plasma potassium from 3.8 to 7.4 meq/liter. Enhanced potassium secretion by the distal tubule, in both control and potassium-adapted animals, is associated with increased aldosterone levels.
对大鼠浅表远端小管进行微灌注研究，以确定远端小管钾分泌与对照饮食和高钾饮食大鼠血浆钾浓度之间的关系。将分级剂量的钾注入对照饮食的动物和接受高钾饮食的动物体内。由于已知大鼠体内钾负荷会抑制近端小管钠和液体重吸收，从而可能导致远端小管非特异性流量相关的钾分泌刺激，因此采用恒定流速的连续微灌注技术来测量钾分泌速率。此外，还测量了血浆醛固酮水平并进行了肾脏清除实验。结果表明，局限于远端小管后期细胞的钾分泌在血浆钾浓度约为6毫当量/升时达到最大速率。在血浆钾浓度从3.8到7.4毫当量/升的范围内，与对照饮食的动物相比，钾适应性显著增强了钾分泌。在对照动物和钾适应动物中，远端小管增强的钾分泌都与醛固酮水平升高有关。
