Dominguez J H, Juhaszova M, Feister H A
Renal Section, Veterans Administration Medical Center, Indianapolis, IN 46202.
J Lab Clin Med. 1992 Jun;119(6):640-9.
The functional expression of the renal sodium-calcium exchanger has been amply documented in studies on renal cortical basolateral membranes. In perfused renal tubules, other investigators have shown sodium-calcium exchange activity in the proximal convolution of the rat and in the distal convolution, the connecting tubule, and the collecting tubule of the rabbit. In rat proximal tubules, we found that the sodium-calcium exchanger is an important determinant of cytosolic calcium homeostasis, since inhibition of sodium-dependent calcium efflux mode caused a large accumulation of tubular calcium. In membranes from rat proximal tubules sodium-calcium activity was high, and in intact proximal tubules, the tubular sodium-calcium exchanger exhibited a high affinity for cytosolic calcium and had a substantial transport capacity, which may be absolute requirements for the maintenance of stable cytosolic calcium in proximal tubules.
肾钠钙交换体的功能表达在关于肾皮质基底外侧膜的研究中已有充分记载。在灌注的肾小管中，其他研究者已证实在大鼠近端曲管以及兔的远端曲管、连接小管和集合小管中存在钠钙交换活性。在大鼠近端小管中，我们发现钠钙交换体是胞质钙稳态的一个重要决定因素，因为抑制钠依赖性钙外排模式会导致肾小管钙大量蓄积。在大鼠近端小管的膜中，钠钙活性很高，并且在完整的近端小管中，肾小管钠钙交换体对胞质钙表现出高亲和力且具有相当大的转运能力，这可能是维持近端小管稳定胞质钙的绝对必要条件。
