NH4+ conductance in Xenopus laevis oocytes .1. Basic observations

被引:32
作者
Burckhardt, BC
Burckhardt, G
机构
[1] Zentrum Physiol. Pathophysiologie, Georg-August-Universität, D-37073 Göttingen
来源
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY | 1997年 / 434卷 / 03期
关键词
Xenopus laevis oocytes; NH4+ conductance; voltage clamp;
D O I
10.1007/s004240050401
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Current-clamp and voltage-clamp techniques were used to study the effects of NH4+ on the cell membrane conductance in Xenopus laevis oocytes. Superfusing the oocytes with NH,CI resulted in a depolarization of the oocyte's cell membrane potential curd, at a clamp potential of -70 mV, in an inward current. The magnitude of the inward current was proportional to the NH4Cl concentration in the extracellular solution and on membrane potential. The reversal potential, E-rev, was -35.5 +/- 11.6 mV under control conditions and -3.1 +/- 11.0 mV (n = 19) in the presence of NH4Cl (10 mmol/l). Superfusion of the oocytes with nominally Ca2+-free solution affected the NH4Cl-evoked response only marginally. Replacement of extracellular Na+ by N-methyl-D-glucamine(+) markedly reduced, but did not eliminate, the NH4Cl-sensitive current and shifted the reversal potential to more negative potentials. The NH4Cl-induced current was substantially inhibited by 0.1 mmol/l flufenamate, and was less affected by blockers of the endogenous K+ conductance, Ba2+ and isosorbiddinitrate (ISDN). The results are compatible with the activation of a conductance by NH4Cl for Na+ and NH4+. The mechanism by which NH4Cl activates the conductance remains unknown.
引用
收藏
页码:306 / 312
页数:7
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