McCall D
J Gen Physiol. 1976 Nov;68(5):537-49. doi: 10.1085/jgp.68.5.537.
Monolayer cultures of myocardial cells were prepared by trypsin dispersion of neonatal rat ventricles. The cells were cultured for 4-5 days by which time a synchronously contracting monolayer of some 1.0 x 10(6) cells per 6-cm diam petri dish had formed. The contraction frequency and Na influx of the cells were unaffected by tetrodotoxin (2 x 10(-5) mg/ml) but both were markedly reduced by the addition of verapamil (10(-9) M to 10(-5) M). The effect of verapamil on both parameters occurred very rapidly. Although unresponsive to change in [Ca]0 between 0.3 mM and 3.0 mM, the contraction frequency of the cells declined rapidly as the [Ca]0 was reduced below 0.3 mM. On the other hand the beating rate of the cells was linearly related to [Na]0 below 40 mM the cells ceased to contract. It is therefore apparent that both [Ca]0 and [Na]0 contribute to the maintenance of the contraction frequency of cultured myocardial cells, but the latter is by far the more important. There also appeared to be, under all conditions, a close relationship between verapamilsensitive Na influx and contraction frequency. For the greater part this relationship was linear although at higher Na influx values it appeared to show evidence of saturation.
通过胰蛋白酶分散新生大鼠心室制备心肌细胞单层培养物。细胞培养4 - 5天，此时每6厘米直径培养皿中形成了约1.0×10⁶个细胞的同步收缩单层。细胞的收缩频率和钠内流不受河豚毒素（2×10⁻⁵毫克/毫升）影响，但加入维拉帕米（10⁻⁹摩尔/升至10⁻⁵摩尔/升）后两者均显著降低。维拉帕米对这两个参数的影响出现得非常迅速。尽管细胞对0.3毫摩尔至3.0毫摩尔之间的[Ca]₀变化无反应，但当[Ca]₀降至0.3毫摩尔以下时，细胞的收缩频率迅速下降。另一方面，细胞的搏动率与[Na]₀呈线性关系，低于40毫摩尔时细胞停止收缩。因此，很明显[Ca]₀和[Na]₀都有助于维持培养心肌细胞的收缩频率，但后者迄今为止更为重要。在所有条件下，维拉帕米敏感的钠内流与收缩频率之间似乎也存在密切关系。在很大程度上，这种关系是线性的，尽管在较高的钠内流值时似乎显示出饱和的迹象。
