Actions of cADP-ribose and its antagonists on contraction in guinea pig isolated ventricular myocytes. Influence of temperature.
Actions of cADP-ribose and its antagonists on contraction in guinea pig isolated ventricular myocytes. Influence of temperature.
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DOI：
10.1161/01.res.81.5.879
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发表时间：
1997-11
影响因子：
20.1
通讯作者：
Shigeo Iino;Yi Cui;A. Galione;D. Terrar
中科院分区：
文献类型：
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作者：
Shigeo Iino;Yi Cui;A. Galione;D. Terrar
尽管人们普遍认为 cADP-核糖 (cADPR) 可以调节海胆卵和多种哺乳动物细胞类型内质网的钙释放，但这种物质是否会影响心肌兴奋-收缩耦合过程中的钙释放仍存在争议。我们研究了 cADPR 在从豚鼠心室分离的完整细胞中的可能作用，特别注意温度可能的影响。在 36 摄氏度下，肌细胞收缩受到 cADPR 胞质应用的影响，且呈浓度依赖性（显示通过贴片吸管在以 1 Hz 刺激激发动作电位的心肌细胞中应用 5 mumol/L cADPR 时，收缩增加约 30%）。使用 fura 2 测量的钙瞬变也增加了 5 mumol/L cADPR。 cADPR 拮抗剂可减少 36 ℃ 下的收缩（通过贴片移液管施加 50 mumol/L 8-Br-cADPR 或 5 mumol/L 8-amino-cADPR 时，收缩约减少 35%）。在室温（约 20 摄氏度至 24 摄氏度）下，cADPR 或其拮抗剂均未检测到对收缩的显着影响。在 36 摄氏度下，用 2 mumol/L 兰尼碱和 1 mumol/L 毒胡萝卜素的混合物处理细胞以抑制肌浆网钙储存的功能，从而阻止通过贴片移液管施加的 5 mumol/L cADPR 的作用。这些观察结果与胞质 cADPR 在 36 摄氏度下增强豚鼠心室肌细胞肌浆网中钙诱导的钙释放的作用一致。在我们的实验条件下观察到的温度影响是可能有助于解释在以前的一些研究中未能检测到 cADPR 及其类似物的作用的一个因素。
Although it is becoming widely accepted that cADP-ribose (cADPR) can regulate calcium release from the endoplasmic reticulum in sea urchin eggs and in a variety of mammalian cell types, it remains controversial whether this substance might influence calcium release during excitation-contraction coupling in cardiac muscle. We have investigated possible actions of cADPR in intact cells isolated from guinea pig ventricle, paying particular attention to the possible influence of temperature. At 36 degrees C, myocyte contraction was influenced by cytosolic application of cADPR in a concentration-dependent manner (showing an approximately 30% increase in contraction with 5 mumol/L cADPR applied via a patch pipette in myocytes stimulated to fire action potentials at 1 Hz). Calcium transients measured with fura 2 were also increased by 5 mumol/L cADPR. Antagonists of cADPR reduced contraction at 36 degrees C (by approximately 35% with either 50 mumol/L 8-Br-cADPR or 5 mumol/L 8-amino-cADPR applied via the patch pipette). At room temperature (approximately 20 degrees C to 24 degrees C), no significant effects on contraction were detected with either cADPR or its antagonists. At 36 degrees C, treatment of the cells with a mixture of 2 mumol/L ryanodine and 1 mumol/L thapsigargin to suppress function of the sarcoplasmic reticulum stores of calcium prevented the action of 5 mumol/L cADPR applied via a patch pipette. These observations are consistent with an action of cytosolic cADPR to enhance calcium-induced calcium release from the sarcoplasmic reticulum in guinea pig ventricular myocytes at 36 degrees C. The observed influence of temperature under the conditions of our experiments is one factor that might help to account for failure to detect actions of cADPR and its analogues in some previous studies.