Touraki M, Beis I
Laboratory of Animal Physiology, School of Sciences, University of Thessaloniki, Greece.
J Exp Zool. 1991 Sep;259(3):287-93. doi: 10.1002/jez.1402590303.
The effect of inorganic slow channel blockers on the calcium paradox in the frog heart was examined. Addition of the divalent cations of manganese, cobalt, nickel, or barium during calcium depletion protected the frog heart against a calcium paradox. This protective effect was indicated by reduced protein release, maintenance of electrical activity, and recovery of mechanical activity during reperfusion. Tissue calcium determination results showed that in the control paradox in the absence of divalent cations, there is an efflux of calcium from myocardial cells during calcium depletion and a massive influx of calcium during the following reperfusion, leading to a calcium overload. Divalent cations protected frog myocardial cells, when present in the calcium-free perfusion medium, by reducing both calcium efflux during calcium depletion and the massive calcium influx during reperfusion. The effectiveness of the added divalent cations showed a strong dependence upon their ionic radius. The most potent inhibitors of the calcium paradox in the frog heart were the divalent cations having an ionic radius closer to the ionic radius of calcium. These results are discussed in terms of the possible mechanism involved in the protective effect of manganese, cobalt, nickel, and barium.
研究了无机慢通道阻滞剂对蛙心钙反常的影响。在钙缺失期间添加锰、钴、镍或钡的二价阳离子可保护蛙心免受钙反常的影响。这种保护作用表现为再灌注期间蛋白质释放减少、电活动维持以及机械活动恢复。组织钙测定结果表明，在无二价阳离子的对照反常中，钙缺失期间心肌细胞有钙外流，随后的再灌注期间有大量钙内流，导致钙超载。当存在于无钙灌注培养基中时，二价阳离子通过减少钙缺失期间的钙外流和再灌注期间的大量钙内流来保护蛙心肌细胞。添加的二价阳离子的有效性与其离子半径密切相关。蛙心钙反常最有效的抑制剂是离子半径与钙的离子半径更接近的二价阳离子。从锰、钴、镍和钡的保护作用可能涉及的机制方面对这些结果进行了讨论。
