An electrophysiological study on miniature Ca relelase from the sarcoplasmic reticulum in cardiac myocytes.

心肌细胞肌浆网微型 Ca 释放酶的电生理学研究。

• 批准号: 63570040
• 负责人: EHARA Tsuguhisa
• 金额: $ 1.41万
• 依托单位: Saga Medical School (1989)Kyushu University (1988)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1988
• 资助国家: 日本
• 起止时间: 1988 至 1989
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63570040/
• 关键词: Ca^<2+>-mediated ion channel; sarcoplasmic reticulum; whole cell recording; caffeine; Ca release; 心室筋細胞

Abstract. In order to examine the effects of increased intracellular Ca^<2+> level on the membrane electrical activity, caffeine, the agent which facilitates Ca^<2+> release from the sarcoplasmic reticulum, was applied to single ventricular cells of the guinea-pig, under condition of the whole cell recording. Caffeine (10 - 25 mM) induced a burst of pulse-like small inward currents. The amplitude of the pulse-like inward currents, which appeared to have a unit magnitude, decreased as the membrane was depolarized, and the reversal potential was estimated to be near 0 mV. Thus, the responsible ion channel may have a unit conductance of 250 - 300 pS. The pulse-like activity persisted when external NaCl was replaced with LiCl, but it disappeared in Tris-Cl solution. Large depolarizations producing sustained cell shortening or intracellular Ca^<2+>-injection enhanced the pulse-like events, suggesting a role of intracellular Ca^<2+> in this phenomenon. Ni^<2+> ions partially inhibited the pulse-like activity. Thus, the ventricular cells appeared to have Ca^<2+>-mediated cation channels with a large conductance, but possible involvement of a specific action of caffeine in the channel activation was not excluded.

抽象的。为探讨细胞内钙离子水平升高对膜电活动的影响，在全细胞记录条件下，应用促进肌浆网钙离子释放的咖啡因作用于豚鼠单个心室肌细胞。咖啡因(10-25 mM)引起脉冲状小内向电流的爆发。随着膜的去极化，脉冲状内向电流的幅度逐渐减小，翻转电位估计接近0 mV。因此，负责任的离子通道可以具有250-300ps的单位电导。当用LiCl代替外加的氯化钠时，这种脉冲状活性仍然存在，但在Tris-Cl溶液中它消失了。大量的去极化产生持续的细胞缩短或细胞内钙离子注入增强了脉搏样事件，提示细胞内钙离子在这一现象中起作用。Ni~(2+)~(2+)对脉冲状活性有部分抑制作用。因此，心室肌细胞似乎具有钙离子介导的大电导阳离子通道，但不排除咖啡因参与通道激活的特定作用。

项目成果

Ehara, T.: J. Physiol. (1989)

Ehara, T.：J. Physiol。

Ehara,T.: "Measurement of reversal potential of Na/Ca exchange current in single ventricular cells of guinea-pig." J.Physiol.410. 227-249 (1989)

Ehara,T.：“测量豚鼠单心室细胞中 Na/Ca 交换电流的反转电位。”

Ehara,T.: "Anion channels activated by adrenaline in cardiac myocytes." Nature. (1990)

Ehara,T.：“心肌细胞中肾上腺素激活的阴离子通道。”

Ehara, T.: J. Physiol.403. 117-133 (1988)

Ehara，T.：J.Physiol.403。

Matsuoka, S.: "Reversal potential of the Na-Ca exchange current in the cardiac myocyte of the guinea-pig." Biomed. Res. Suppl., 2: 149-152, 1989.

Matsuoka, S.：“豚鼠心肌细胞中 Na-Ca 交换电流的逆转电位。”