Srivastava R D
Indian J Physiol Pharmacol. 1985 Oct-Dec;29(4):239-44.
Spontaneously beating isolated atria of rabbits responded to Mn++ and Co++ with a progressively increasing negative chronotropism and inotropism, which was reversible by washout and by elevating the bath concentration of Ca++. The cumulative dose response curve for adrenaline for chronotropic response was markedly shifted to the right in the presence of Mn++ or Co++. This effect was also reversible. Verapamil produced only a moderate decline in spontaneous rate and contractility and did not block the chronotropic response to adrenaline. It is concluded that Mn++ and Co++ block the action of catecholamine on the pacemaker cells and they differ at least in part from organic calcium channel antagonists in their mechanism of action.
兔离体自发搏动的心房对Mn++和Co++的反应是负性变时性和变力性逐渐增强，通过冲洗以及提高浴液中Ca++浓度可使其逆转。在存在Mn++或Co++的情况下，肾上腺素变时反应的累积剂量反应曲线显著右移。这种效应也是可逆的。维拉帕米仅使自发频率和收缩性适度下降，且不阻断对肾上腺素的变时反应。结论是，Mn++和Co++阻断儿茶酚胺对起搏细胞的作用，其作用机制至少部分不同于有机钙通道拮抗剂。
