ZINC MODULATION OF A TRANSIENT POTASSIUM CURRENT AND HISTOCHEMICAL-LOCALIZATION OF THE METAL IN NEURONS OF THE SUPRACHIASMATIC NUCLEUS

被引:48
作者
HUANG, RC [1 ]
PENG, YW [1 ]
YAU, KW [1 ]
机构
[1] JOHNS HOPKINS UNIV, SCH MED, DEPT NEUROSCI, BALTIMORE, MD 21205 USA
关键词
D O I
10.1073/pnas.90.24.11806
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The effect of Zn2+ on a voltage-dependent, transient potassium current (I(A)) in acutely dissociated neurons from the suprachiasmatic nucleus was studied with the whole-cell patch-clamp technique. At micromolar concentrations, Zn2+ markedly potentiated I(A) activated from a holding potential of -60 mV, which is the resting potential of these neurons. This potentiation occurred at a Zn2+ concentration as low as 2 muM and increased with higher Zn2+ concentrations. The Zn2+ action appears to arise from a shift in the steady-state inactivation of I(A) to more positive voltages. At 30 muM, Zn2+ shifted the half-inactivation voltage by +20 mV (from -80 mV to -60 mV), and 200 muM Zn2+ shifted this voltage by +45 mV (from -80 mV to -35 mV). Histochemically, we have also observed Zn2+ staining throughout the suprachiasmatic nucleus; the staining is particularly intense in the ventrolateral region of the nucleus, which receives the major fiber inputs. Our findings suggest that Zn2+, presumably synaptically released, may modulate the electrical activity of suprachiasmatic nucleus neurons through I(A). Because vesicular Zn2+ is fairly wide-spread in the central nervous system, it is conceivable that this kind of Zn2+ Modulation on I(A), and possibly on other voltage-activated currents, exists elsewhere in the brain.
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页码:11806 / 11810
页数:5
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