Lehto H, Tirri R
Acta Physiol Scand. 1980 Dec;110(4):385-9. doi: 10.1111/j.1748-1716.1980.tb06685.x.
Myocardial cell groups, mechanically disaggregated from the rat heart, beat spontaneously in a medium which resembles intracellular fluid. The cells, initially functioning in an uncoordinated way, i.e. each cell in its own rhythm, gradually become coordinated as a function of time. After 90 min of incubation at 15 degrees C all the cell groups were functioning in a coordinated way. The initiation of coordination was temperature-dependent. Lowering the temperature from 15 degrees C to 10 degrees C significantly delays the coordination, only 75% of the cell groups being coordinated after 90 min. The contraction wave in coordinated cell groups was very slow; 90 +/- 7 micrometers/s at 20 degrees C, 100 +/- 6 micrometers/s at 30 degrees C and 100 +/- 7 micrometers/s at 35 degrees C. The velocity of contraction waves was not significantly temperature-dependent, suggesting a neonenzymatical type of propagation. It also seems too slow to be an electrical event. Apparently the contraction waves are propagated by diffusion of Ca2+. The addition of caffeine to the medium hastened the coordination of contractions, but Na-azide strongly inhibited it. The results indicate that the sarcoplasmic reticulum functions in the coordination of contractions, probably by releasing Ca2+ for the activation of the myofilaments.
从大鼠心脏机械分离得到的心肌细胞群，在类似细胞内液的培养基中能自发搏动。这些细胞最初以不协调的方式运作，即每个细胞都有自己的节律，随着时间的推移逐渐变得协调。在15℃孵育90分钟后，所有细胞群都以协调的方式运作。协调的起始依赖于温度。将温度从15℃降至10℃会显著延迟协调，90分钟后只有75%的细胞群实现协调。协调的细胞群中的收缩波非常缓慢；在20℃时为90±7微米/秒，在30℃时为100±6微米/秒，在35℃时为100±7微米/秒。收缩波的速度没有明显的温度依赖性，提示为新酶促类型的传播。它似乎也太慢而不可能是电活动。显然，收缩波是通过Ca2+的扩散进行传播的。向培养基中添加咖啡因会加速收缩的协调，但叠氮化钠会强烈抑制它。结果表明，肌浆网在收缩的协调中起作用，可能是通过释放Ca2+来激活肌丝。
