Electrophysiological study on the physiological roles of the oscillatory release of calcium from the sarcoplasmic reticulum in myocardium.

心肌肌浆网振荡释放钙的生理作用的电生理学研究。

• 批准号: 61570048
• 负责人: EHARA Tsuguhisa
• 金额: $ 1.47万
• 依托单位: Kyushu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1986
• 资助国家: 日本
• 起止时间: 1986 至 1987
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61570048/
• 关键词: Oscillatory release of calcium; Sarcoplasmic reticulum; Myocardium; Calcium homeostasis; Calcium-mediated conductance; Ca依存性陽イオンチャネル; パッチクランプ; カフェイン; 心筋; 小胞体; カルシウム放出; カルシウム排出機構; カルシウムホメオスタシス; 膜電位; 膜電流; イオンチャネル

The electrical and mechanical activities related to the oscillatory release of Ca from the sarcoplasmic reticulum (SR) were studied in muscle preparations and single myocytes isolated from guinea-pig ventricles. In partially depolarized papillary muscles, rapid stimulation (1 Hz) in the presence of <beta>-adrenergic stimulants induced oscillatory afterpotentials (OAP) and aftercontractions (AC) which were produced by the oscillatory release of Ca from SR. Mg ions at concentrations of 5-12 mM were found to suppress these OAP and AC. However, Mg potentiated the twitch contractions, and this effect was due to suppression of the oscillatory release of Ca from SR during diastole. Thus, the Ca oscillation at SR appeared to decrease the amount of Ca in SR avaliable for twitch. Since microscopic Ca oscillations may be present even in normal myocardium, the above results suggest that such oscillaltions can be an important mechanism regulating the amount of Ca in SR as well as the cellular Ca ho … More meostasis, provided there is a link between these oscillations and the Ca-extruding function of the sarcolemma. In voltage-clamped isolated myocytes, high concentrations (15-25 mM) of caffeine, which releases Ca from SR, were found to induce pulse-like small (20-30 pA at the resting potential) inward currents. These currents appeard to be activated by the intracellular Ca, since Ca injection into the cell or application of large depolarizations which produced a tonic tension enhanced them. The currents were Na-dependent but could flow in the presence of Li instead of Na. The pulse-like development suggested that the currents were generated in the membrane sites which distributed relatively scarcely in the sarcolemma. The most probable sites are those facing the juxtamembranous SR. observed currents might reflect one aspect of the functional coupling of the sarcolemma and SR. We are now further studying the nature of these currents. Another type of the Ca-activated electrical event was also noted in isolated myocytes with the patch clamp technique. This was the current through the Ca-activated non-specific cation channel, and its properties were quantiatively analyzed. This current contributes to the Ca-mediated steady background conductance and does not generate pulse-like electrical events in the whole cell level. Less

在豚鼠心室肌制备物和单个肌细胞中研究了与肌浆网（SR）振荡释放Ca有关的电和机械活动。在部分去极化的乳头肌，快速刺激（1 Hz）的存在<beta>下，肾上腺素能兴奋剂诱导振荡后电位（OAP）和后收缩（AC）产生的振荡释放的Ca从SR。镁离子在5-12 mM的浓度被发现抑制这些OAP和AC。然而，镁增强的抽搐收缩，这种效果是由于抑制振荡释放的钙从SR在dipolole。因此，SR处的Ca振荡似乎减少了SR中可用于抽搐的Ca量。由于正常心肌中也可能存在钙振荡，上述结果提示这种振荡可能是调节SR中钙含量以及细胞内钙离子浓度的重要机制。 ...更多信息 如果这些振荡和肌膜的Ca-挤出功能之间存在联系，则可促进肌膜的内稳态。在电压钳位分离的肌细胞中，发现高浓度（15-25 mM）的咖啡因（其从SR释放Ca）诱导脉冲样小（静息电位下20-30 pA）内向电流。这些电流似乎是由细胞内钙激活的，因为钙注入细胞或应用产生紧张性张力的大去极化增强了它们。电流是Na依赖性的，但可以在Li而不是Na的存在下流动。脉冲状的发展表明电流产生于肌膜中分布相对较少的膜部位。最有可能的网站是那些面临的acromembranous SR。所观察到的电流可能反映了一个方面的功能耦合的肌膜和SR。我们现在正在进一步研究这些电流的性质。膜片钳技术在离体心肌细胞中也观察到另一种钙激活的电活动。这是通过钙激活的非特异性阳离子通道的电流，并对其性质进行了定量分析。该电流有助于Ca介导的稳定背景电导，并且在整个细胞水平上不产生脉冲状电事件。少

项目成果

Ito,T.: Amer.J.Physiol.253. H248-H255 (1987)

伊藤，T.：Amer.J.Physiol.253。

Ehara,T.eds.K.Yamada,A.M.Katz and J.Toyama: Arrhythmogenic effects of autonomic transmitters on depolarized ventricular muscle.In Cardiac Function under Ischemia and Hypoxia.9 (1986)

Ehara，T.eds.K.Yamada，A.M.Katz 和 J.Toyama：自主神经递质对去极化心室肌的致心律失常作用。缺血和缺氧下的心脏功能。9（1986）

Imoto,Y.: Amer.J.Physiol.252. H325-H333 (1987)

Imoto，Y.：Amer.J.Physiol.252。

Imoto, Y. et al.: "Voltage- and time-dependent block of i_<K1> underlying Ba^<2+>- induced ventricular automaticity." Amer. J. Physiol.252. H325-H333 (1987)

Imoto, Y. 等人：“Ba^<2> 引起的心室自动性的 i_<K1> 的电压和时间依赖性阻断。”

Ehara, T. et al.: Arrhythmogenic effects of autonomic transmitters on depolarized ventricular muscle. In Cardiac Function under Ischemia and Hypoxia (eds. by K. Yamada, A. M. Katz and J. Toyama). The Nagoya University Press, 123-131 (1986)

Ehara, T. 等人：自主神经递质对去极化心室肌的致心律失常作用。