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大鼠脑mRNA在爪蟾卵母细胞内表达的电压门控钙通道的电压箝研究

姚永, 朱辉, 杨又山, 包永德

中国科学院上海生理研究所. 上海 200031

摘要

该工作用电压箝记录方法研究了爪蟾卵母细胞经注射大鼠脑mRNA后表达的电压门控钙通道。钙通道的特性由通过钙通道的钡离子流[I_(Ba)]来描述。本研究采用的卵母细胞均取自被鉴定的爪蟾。这些爪蟾卵母细胞内源性I_(Ba)大多为零,或小于15nA。将从出生后10d的大鼠全脑中提取的mRNA微量注入这些卵母细胞。在注射mRNA后的5d内,I_(Ba)逐渐增大。在mRNA注射后第三天,由大鼠脑mRNA表达的电压依赖性I_(Ba)最大值一般超过100nA。作为对比,在注射从胚胎大鼠脑提取的mRNA的卵母细胞,几乎测不到电压依赖性I_(Ba)的表达。

关键词： 钙通道; 爪蟾卵母细胞; mRNA表达

A voltage-clamp study on voltage-gated calcium channels translated in Xenopus oocytes by rat brain mRNA

Yao Yong, Zhu Hui, Yang Youshan, Bao Yongde

Shanghai Institute of Physioloyg, Academy Sinica. Shanghai 200031, China

Abstract

Voltage-gated calcium channels，expressed in Xenopas oocytes after injection of
rat brain mRNA，were studied by using voltage-clamp technique. The properties of
the calcium channels were characterized by barium current[I_(Ba)]passed through the channels. All oocytes used in this study were taken from five identified donors. Endogenous voltage-activated barium current measured in most oocytes from these donors were not detectable，or smalleer than 15 nA，mRNA was extracted from the whole brains of 10 day postnatal rats and microin jected into the oocytes. I_(Ba) increased gradually. during five days after mRNA injection. The maximum amplitude of the expressed voltage-activated barium current was usually larger than one hundred of nA on the third day after mRNA injection. In comparison，the expresion of voltage-activated barium current was hardly detectable in oocytes injected by mRNA extracted from brains of embryonic rats. The voltaged-dependence of activation and inactivation pharmacology of I_(Ba) were studied. It was found that I_(Ba) was inhibited potently by lanthanide cations [La~(+3)，Nd~(+3)，Srn~(+3)，Eu~(+3)，Gd~(+3)m, Dy~(+3)，Er~(+3)] at #mu# mol/L concentration level. L-type calcium channel ligands，nifedipineand Bay K 8644 inhibited I_(Ba),at 100 pmol/L，while another dihydropyridine ligand(±)nimodipine enhanced I_(Ba). at the same concentration.

Key words: Calcium channel;Xenopus oocytes;mRNA expression

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引用本文：

姚永, 朱辉, 杨又山, 包永德. 大鼠脑mRNA在爪蟾卵母细胞内表达的电压门控钙通道的电压箝研究[J]. 生理学报 1993; 45 (1): .

Yao Yong, Zhu Hui, Yang Youshan, Bao Yongde. A voltage-clamp study on voltage-gated calcium channels translated in Xenopus oocytes by rat brain mRNA. Acta Physiol Sin 1993; 45 (1): (in Chinese with English abstract).