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角鲨(棘鲨)直肠腺基底外侧膜中的钾通道。

Potassium channels in the basolateral membrane of the rectal gland of the dogfish (Squalus acanthias).

作者信息

Greger R, Gögelein H, Schlatter E

出版信息

Pflugers Arch. 1987 Jun;409(1-2):100-6. doi: 10.1007/BF00584755.

Abstract

Previous studies in isolated, in vitro perfused rectal gland tubules (RGT) have revealed that the basolateral membrane possesses a K+ conductive pathway. In the present study, we have utilized the patch clamp technique in RGT segments to characterize this pathway. The basolateral membrane was approached with patch pipettes at the open end of in vitro perfused segments. Recordings were obtained in cell-attached as well as in excised inside-out patches. In cell-attached patches with the pipette filled with a KCl solution (274 mmol/l) and the bath containing NaCl shark Ringer (275 mmol/l), inward K+ currents (from pipette into cell) with a mean slope conductance of 123 +/- 26 pS (n = 3) were observed. We were unable to generate outward K+ currents at high depolarizing (cell more positive) clamp voltages. This indicates inward rectification of this channel. To examine the rectification properties further, excised (inside out) patches were exposed to K+ concentration gradients, directed out of, as well as into the pipette. With NaCl in the pipette and KCl in the bath, K+ outward currents were observed. The current-voltage (IV) relation revealed Goldman-type rectification, with a mean single channel conductance of 185 +/- 28 pS (n = 7) at high positive voltages (linear range of the IV curve). The single-channel permeability coefficient for K+ was 0.26 +/- 0.04 X 10(-12) cm3/s (n = 7). In the reversed experiment (pipette KCl, bath NaCl), inward currents of similar kinetics and amplitude were obtained. The single channel conductance was 146 +/- 21 pS (n = 7) at high negative voltages (linear range of the IV curve).(ABSTRACT TRUNCATED AT 250 WORDS)

摘要

以往对离体的体外灌注直肠腺小管(RGT)的研究表明,基底外侧膜具有钾离子传导途径。在本研究中,我们利用膜片钳技术对RGT节段中的该途径进行了表征。在体外灌注节段的开口端,用膜片吸管接触基底外侧膜。在细胞贴附式以及切除的内向外膜片中进行记录。在吸管中充满氯化钾溶液(274 mmol/L)且浴槽中含有鲨鱼生理盐水氯化钠(275 mmol/L)的细胞贴附式膜片中,观察到内向钾离子电流(从吸管流入细胞),平均斜率电导为123±26 pS(n = 3)。在高去极化(细胞更正)钳制电压下,我们无法产生外向钾离子电流。这表明该通道具有内向整流特性。为了进一步研究整流特性,将切除的(内向外)膜片暴露于钾离子浓度梯度下,该梯度指向吸管外部以及吸管内部。当吸管中为氯化钠且浴槽中为氯化钾时,观察到钾离子外向电流。电流-电压(IV)关系显示出戈德曼型整流,在高正电压(IV曲线的线性范围)下平均单通道电导为185±28 pS(n = 7)。钾离子的单通道渗透系数为0.26±0.

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