Surges Rainer, Freiman Thomas M, Feuerstein Thomas J
Section of Clinical Neuropharmacology, Department of Neurology, Neurozentrum, Breisacher Strasse 64, 79106, Freiburg i.Br., Germany.
Neurosci Lett. 2002 Oct 31;332(2):136-40. doi: 10.1016/s0304-3940(02)00820-0.
The effects of rises in external K(+) (K(ext)) on I(h) were investigated in CA1 pyramidal cells of rat hippocampal slices using the whole-cell patch clamp technique. At the basal K(ext) level (2.5 mM), hyperpolarization-activated cation current (I(h)) had a maximal amplitude of -350+/-60 pA which was enhanced by approximately 60 and approximately 95% at 5 and 7.5 mM K(ext), respectively. The midpoint activation voltage was significantly shifted from -80 mV in the negative direction to about -87 mV at both 5 and 7.5 mM K(ext), without appreciable alterations of the current kinetics. The maximal conductance was approximately 2.4 nS under control conditions and significantly increased to approximately 3.3 and approximately 5.6 nS at 5 and 7.5 mM K(ext), respectively. The reversal potential was shifted in the positive direction, from a control value of approximately -30 mV by approximately 6 and approximately 14 mV at 5 and 7.5 mM K(ext), respectively. Our data demonstrate that even moderate changes in K(ext) have a substantial effect on the properties of I(h).
采用全细胞膜片钳技术，在大鼠海马脑片CA1锥体细胞中研究了细胞外钾离子（K(ext)）升高对I(h)的影响。在基础K(ext)水平（2.5 mM）时，超极化激活的阳离子电流（I(h)）的最大幅值为-350±60 pA，在K(ext)为5 mM和7.5 mM时，该电流幅值分别增加了约60%和约95%。在5 mM和7.5 mM K(ext)时，激活电压中点均从-80 mV显著向负向移动至约-87 mV，电流动力学无明显改变。对照条件下最大电导约为2.4 nS，在5 mM和7.5 mM K(ext)时分别显著增加至约3.3 nS和约5.6 nS。反转电位向正向移动，在5 mM和7.5 mM K(ext)时，分别从对照值约-30 mV移动了约6 mV和约14 mV。我们的数据表明，即使K(ext)发生适度变化也会对I(h)的特性产生显著影响。
