Dipolo R, Marty A
IVIC-Department of Biophysics, Caracas, Venezuela.
Biophys J. 1989 Mar;55(3):571-4. doi: 10.1016/S0006-3495(89)82850-4.
Isolated cells from rat lacrimal glands were voltage clamped using the tight-seal whole-cell recording technique. The intracellular solution contained ATP and an elevated Na concentration (70 mM). Removing external K ions elicited an inward current shift. Ouabain (0.5 mM) induced an inward current shift of identical amplitude, but with slower kinetics. In the presence of ouabain, removal of K ions did not alter the cell current. The potassium- and ouabain-sensitive current was outward between -120 and +20 mV, and its amplitude decreased below -60 mV. This current was highly sensitive to temperature, and was not affected by blockers of the K channels which are present in these cells. It was attributed to an inhibition of the Na-K pump. The Na-K pump current was estimated to be 15 pA for an average acinar cell at physiological temperature, with 70 mM internal Na ions and 20 mM external K ions. Implications of this value in terms of electrolyte secretion are discussed.
采用紧密封接全细胞记录技术对大鼠泪腺分离细胞进行电压钳制。细胞内溶液含有ATP和升高的Na浓度（70 mM）。去除细胞外K离子会引起内向电流偏移。哇巴因（0.5 mM）诱导相同幅度的内向电流偏移，但动力学较慢。在存在哇巴因的情况下，去除K离子不会改变细胞电流。钾离子和哇巴因敏感电流在-120至+20 mV之间为外向电流，其幅度在-60 mV以下降低。该电流对温度高度敏感，不受这些细胞中存在的K通道阻滞剂的影响。它归因于Na-K泵的抑制。对于生理温度下平均腺泡细胞，在细胞内有70 mM Na离子和细胞外有20 mM K离子的情况下，Na-K泵电流估计为15 pA。讨论了该值在电解质分泌方面的意义。
