The hypothesis that calcium release from the sarcoplasmic reticulum in cardiac muscle is induced by rises in free cytosolic calcium (Fabiato 1983, Am. J. Physiol 245) allows the possibility that the release could be at least partly regenerative. There would then be a non-linear relation between calcium current and calcium release. We have investigated this possibility in a single-cell version of the rabbit-atrial model developed by Hilgemann & Noble (1987, Proc. R. Soc. Lond. B 230). The model predicts different voltage ranges of activation for calcium-dependent processes (like the sodium-calcium exchange current, contraction or Fura-2 signals) and the calcium current, in agreement with the experimental results obtained by Earm et al. (1990, Proc. R. Soc. Lond. B 240) on exchange current tails, Cannell et al. (1987, Science, Wash. 238) by using Fura-2 signals, and Fedida et al. (1987, J. Physiol., Lond. 385) and Talo et al. (1988, Biology of isolated adult cardiac myocytes) by using contraction. However, when the Fura-2 concentration is sufficiently high (greater than 200 microM) the activation ranges become very similar as the buffering properties of Fura-2 are sufficient to remove the regenerative effect. It is therefore important to allow for the buffering properties of calcium indicators when investigating the correlation between calcium current and calcium release.

中文翻译：

---

单个心房细胞模型：钙电流与钙释放之间的关系。

游离肌钙的升高引起心肌肌浆网中钙释放的假说（Fabiato 1983，Am。J. Physiol 245），使得释放可能至少是部分再生的可能性。钙电流和钙释放之间将存在非线性关系。我们已经在Hilgemann＆Noble（1987，Proc。R. Soc。Lond。B 230）开发的兔心房模型的单细胞版本中研究了这种可能性。该模型预测了钙依赖性过程（如钠钙交换电流，收缩或Fura-2信号）和钙电流的不同激活电压范围，与Earm等人获得的实验结果一致。（1990，Proc.R.Soc.Lond.B 240）关于交换电流尾巴的研究，Cannell等人。（1987年，科学，华盛顿。238），使用Fura-2信号，以及Fedida等。（1987，J.Physiol。，Lond.385）和Talo等人（1987）。（1988，分离的成年心肌细胞的生物学）通过使用收缩。但是，当Fura-2浓度足够高（大于200 microM）时，激活范围将变得非常相似，因为Fura-2的缓冲特性足以消除再生作用。因此，在研究钙电流与钙释放之间的相关性时，重要的是要考虑钙指示剂的缓冲特性。当Fura-2的浓度足够高（大于200 microM）时，激活范围将变得非常相似，因为Fura-2的缓冲特性足以消除再生作用。因此，在研究钙电流与钙释放之间的相关性时，重要的是要考虑钙指示剂的缓冲特性。当Fura-2的浓度足够高（大于200 microM）时，激活范围变得非常相似，因为Fura-2的缓冲特性足以消除再生作用。因此，在研究钙电流与钙释放之间的相关性时，重要的是要考虑钙指示剂的缓冲特性。