【摘要】 本实验应用离子选择性微电极方法，动态监测了Ｎｉ２＋对心肌细胞Ｎａ＋、Ｋ＋活度的影响，并以细胞内Ｎａ＋逐出速率［ｄ（ａｉＮａ）／ｄｔ］作为膜钠泵活动度的指标，观察了Ｎｉ２＋对膜钠泵活动的影响。结果显示：（１）在本实验浓度下Ｎｉ２＋对静息及活动（自律或电刺激）的细胞内Ｎａ＋、Ｋ＋活度无明显影响；（２）可使细胞外Ｋ＋活度升高；（３）便刺激停止即刻细胞内Ｎａ＋逐出速率下降；（４）减小无钠无钙液引起的细胞外Ｋ＋活度下降幅度。结果提示：Ｎｉ２＋对处于高水平活动的心肌细胞膜钠泵具有明显的抑制作用，而对处于一般活动状态的膜钠泵则未见有明显影响；在Ｎｉ２＋存在下心肌细胞膜对Ｋ＋的通透性有不同程度的提高。更多还原

【Abstract】 The effects of Ni2+ on Na+ and K+ activities and on sodium-pump activity in myocardium were investigated. The intracellular sodium activity (aiNa), intracellular potassium activity (aiK), extracellular potassium activity (a0K), and declining rate of a1Na at the very end of a train stimulation [d(a1Na)/dt, used as an index of sodium-pump activity] were measured with Na+-and K+-selective microelectrodes in sheep cardiac Purkinje fibers and guinea-pig ventricular trabeculae superfused with Tyrode solution with or without Ni2+. The results showed that Ni2+ did not significantly affect the levels of aiNa and aiK, but increased a0K when the preperations were quiescent or driven. In the presence of Ni2+, d(aiNa)/dt was slowed down markedly, and the decrease in a0K induced by Na+, Ca2+-free solution was reduced or reversed.The results suggest that Ni2+ exhibits marked inhibitory effect on sodium-pump only when the latter is at a high level of activity, while there is no appreciable influence on sodium-pump at its common activity level. In addition, in the presence of Ni2+, the membrane permeability to K+ might be increased to various degrees.更多还原