CAMP-DEPENDENT INWARD RECTIFIER CURRENT IN NEURONS OF THE RAT SUPRACHIASMATIC NUCLEUS

被引:21
作者
AKASU, T
SHOJI, S
机构
[1] Department of Physiology, Kurume University School of Medicine, Kurume, 830
来源
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY | 1994年 / 429卷 / 01期
关键词
SCN; VOLTAGE-CLAMP; INWARD RECTIFIER CURRENT (I-H); CAMP; FORSKOLIN;
D O I
10.1007/BF02584037
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Electrophysiological properties of the inward rectification of neurons in the rat suprachiasmatic nucleus (SCN) were examined by using the single-electrode voltage-clamp method, in vitro. Inward rectifier current (I-H) was produced by hyperpolarizing step command potentials to membrane potentials negative to approximately -60 mV in nominally zero-Ca2+ Krebs solution containing tetrodotoxin (1 mu M), tetraethylammonium (40 mM), Cd2+ (500 mu M) and 4-aminopyridine (1 mM). I-H developed during the hyperpolarizing step command potential with a duration of up to 5 s showing no inactivation with time. I-H was selectively blocked by extracellular Cs+ (1 mM). The activation of the H-channel conductance (G(H)) ranged between -55 and -120 mV. The G(H) was 80-150 pS (n=4) at the half-activation voltage of -84+/-7 mV (n=4). The reversal potential of I-H obtained by instantaneous current voltage (I/V) relations was -41+/-6 mV (n=4); it shifted to -51+/-8 mV (n=3) in low-Na+ (20 mM) solution and to -24+/-4 mV (n=4) in high-K+ (20 mM) solution. Forskolin (1-10 mu M) produced an inward current and increased the amplitude of I-H. Forskolin did not change the half-activation voltage of G(H). 8-Bromo-adenosine 3',5'-cyclic monophosphate (8-Br-cAMP, 0.1-1 mM) and dibutyryl-cAMP (0.1-1 mM) enhanced I-H. 3-Isobutyl-1-methylxanthine (IBMX, 1 mM) also enhanced I-H. The results suggest that the inward rectifier cation current is regulated by the basal activity of adenylate cyclase in neurons of the rat SCN.
引用
收藏
页码:117 / 125
页数:9
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