钙离子与牛磺酸两者跨心肌细胞膜内流的相互影响

Interrelationship between calcium influx and taurine influx in cultured rat cardiomyocytes

目的和方法：取新生ＳＤ大鼠心室肌制备培养搏动心肌细胞，采用放射性同位素４５Ｃａ２＋及３Ｈ－牛磺酸示踪技术，观察钙离子与牛磺酸跨心肌细胞膜内流的相互影响。结果：（１）牛磺酸内流在低胞外Ｃａ２＋浓度（［Ｃａ２＋］ｏ，０．５ｍｍｏｌ／Ｌ）和高［Ｃａ２＋］ｏ（４０ｍｍｏｌ／Ｌ）均比正常［Ｃａ２＋］ｏ（１５ｍｍｏｌ／Ｌ）和高［Ｃａ２＋］ｏ（４０ｍｍｏｌ／Ｌ）时增加，尤以低［Ｃａ２＋］。时明显；异搏定（１０μｍｏｌ／Ｌ）能促进牛磺酸的内流；（２）１０～２０ｍｍｏｌ／Ｌ牛磺酸对不同［Ｃａ２＋］。（０５、１５和４０ｍｍｏｌ／Ｌ）下的Ｃａ２＋内流均有抑制作用，而１ｍｍｏｌ／Ｌ牛磺酸只抑制高［Ｃａ２＋］ｏ时Ｃａ２＋内流，对低［Ｃａ２＋］ｏ和正常［Ｃａ２＋］ｏ时Ｃａ２＋内流无明显作用；１～２０ｍｍｏｌ／Ｌβ－丙氨酸对Ｃａ２＋内流无明显影响。结论：胞外Ｃａ２＋浓度的变化可直接影响牛磺酸内流，而牛磺酸能抑制Ｃａ２＋的内流，两者相互影响。

AIM and METHOD:Monolayer culture of spontaneously contracting rat heart cells were obtained from newborn SD rats and seeded into culture plates.The Interrelationship between calcium influx and taurine influx was investigated by using radioactive isotope( 45 Ca 2+ and 3 H-taurine)tracing techniques.RESULTS:(1)Low extracellular calcium concentration([Ca 2+ ] o,0 5mmol/L)and high [Ca 2+ ] o(4 0mmol/L)could accelerate the taurine influx,especially in low [Ca 2+ ] o;The increased taurine influx was also detected when verapamil(10μmol/L)was added to the medium;(2)10～20mmol/L of taurine have an inhibitory effect on Ca 2+ influx in different level of [Ca 2+ ] o(i.e.:0 5,1 5 and 4 0mmol/L);1mmol/L of taurine had the same effect only when [Ca 2+ ] o was at 4 0mmol/L and without any effect when [Ca 2+ ] o was at 1 5 or 0 5mmol/L;1～20mmol/L β-alanine, a carboxylic analog of taurine,have no effect on Ca 2+ influx.CONCLUSION:Taurine could exert its influence upon intracellular calcium by means of restraining the calcium influx,especially under changed of [Ca 2+ ] o,which could facilitate the taurine influx and thus enhance the intracellular taurine content.