Morad M, Cleemann L
J Mol Cell Cardiol. 1987 Jun;19(6):527-53. doi: 10.1016/s0022-2828(87)80360-7.
Role of Ca2+ Channel in Development of Tension in Heart Muscle. Journal of Molecular and Cellular Cardiology (1987) 19, 527-553. In mammalian and amphibian hearts Ca2+ enters the myocardial cells via voltage-gated Ca2+ channels. The role of Ca2+ channels in transporting the activator Ca2+ was probed by examining the redevelopment of tension and ICa in voltage-clamped myocardial strips after step recovery of Ca2+ channel from photolabile Ca2+ antagonist. Comparison of the kinetics of redevelopment of tension in the frog and mammalian heart following the photoinactivation of Ca2+ channel blockers showed that in the frog heart tension redevelops fully in one beat, while 5 to 7 beats were required for full redevelopment of tension in the mammalian heart. Ca2+ depletion studies using Antipyrylazo III showed that extracellular Ca2+ depletion during the action potential occurs primarily via the Ca2+ channel. In the frog heart sufficient Ca2+ is transported from the extracellular space during a single beat to activate tension. In the mammalian heart ICa triggers the release of internal stores, which when only fully loaded caused full development of tension. ICa also was involved in loading the intracellular Ca2+ pools. Two types of Ca2+ channels have been identified in the mammalian myocytes. The low-threshold rapidly inactivating Ca2+ channels appear to be involved in trigger release of Ca2+, while the high threshold (conventional Ca2+ channels) seem to be involved primarily in reloading of internal Ca2+ pools.
钙离子通道在心肌张力发展中的作用。《分子与细胞心脏病学杂志》（1987年）19卷，527 - 553页。在哺乳动物和两栖动物心脏中，钙离子通过电压门控钙离子通道进入心肌细胞。通过检测在光不稳定钙离子拮抗剂作用后电压钳制心肌条带中张力和钙离子电流（ICa）的重新恢复情况，探讨了钙离子通道在转运激活钙离子方面的作用。比较钙离子通道阻滞剂光灭活后青蛙和哺乳动物心脏中张力重新恢复的动力学，结果表明，青蛙心脏中张力在一次心跳中完全恢复，而哺乳动物心脏中张力完全恢复则需要5至7次心跳。使用安替比拉宗III进行的钙离子耗竭研究表明，动作电位期间细胞外钙离子耗竭主要通过钙离子通道发生。在青蛙心脏中，单次心跳期间从细胞外空间转运足够的钙离子以激活张力。在哺乳动物心脏中，钙离子电流触发内部储存库的释放，只有当储存库完全充满时才会导致张力完全发展。钙离子电流也参与了细胞内钙离子池的装载。在哺乳动物心肌细胞中已鉴定出两种类型的钙离子通道。低阈值快速失活的钙离子通道似乎参与钙离子的触发释放，而高阈值（传统钙离子通道）似乎主要参与内部钙离子池的重新装载。
