Gusev Gennadii P, Agalakova Natalia I, Ivanova Tatiana I
Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Thorez pr. 44, 194223 St. Petersburg, Russia.
Gen Physiol Biophys. 2008 Dec;27(4):284-90.
Lithium, capable of replacing Na+ in various membrane transport processes, was used to investigate Na+ transport pathways across the lamprey erythrocytes membrane. The values of Li+ influxes have ranged from 8 to 24 mmol/l cells/h. Intracellular accumulation of Li+ was associated with loss of cellular Na+, the value of which was less than the value of Li+ influx. Both Li+ influx and Na+ efflux were partially inhibited by amiloride. The amiloride-sensitive Li+ influx was considerably stimulated by hyperosmotic cell shrinkage. The treatment of lamprey erythrocytes with blockers of protein phosphatases (fluoride and cantharidin) also resulted in a considerable increase in Li+ accumulation within the cells. No significant difference was observed between the values of Li+ and Na+ (22Na) influxes measured in red cells incubated simultaneously in isotonic LiCl and NaCl media (9.2 +/- 2.1 and 7.8 +/- 1.3 mmol/l cells/h, respectively). In hypo- and hypertonic media, however, the rate of Na+ influx in lamprey erythrocytes was approximately twice higher as compared to the rate of Li+ influx, what was determined by the difference in the amiloride-sensitive components. In acidified lamprey erythrocytes (intracellular pH 6.0) Li+ and Na+ influxes were considerably increased due to activation of amiloride-sensitive Na+/H+ (Li+/H+) exchange mechanism, although the activity of Na+/H+ exchange was much greater than that of Li+/H+ exchange. The data obtained confirm the hypothesis on the presence of two amiloride-sensitive systems of Na+ transport in the lamprey red blood cells.
锂能够在各种膜转运过程中替代Na⁺，被用于研究穿过七鳃鳗红细胞膜的Na⁺转运途径。Li⁺内流的值在8至24 mmol/升细胞/小时范围内。Li⁺在细胞内的积累与细胞内Na⁺的丢失相关，其值小于Li⁺内流的值。Li⁺内流和Na⁺外流均被氨氯吡脒部分抑制。氨氯吡脒敏感的Li⁺内流受到高渗性细胞皱缩的显著刺激。用蛋白磷酸酶抑制剂（氟化物和斑蝥素）处理七鳃鳗红细胞也导致细胞内Li⁺积累显著增加。在等渗LiCl和NaCl培养基中同时孵育的红细胞中测量的Li⁺和Na⁺（²²Na）内流值之间未观察到显著差异（分别为9.2±2.1和7.8±1.3 mmol/升细胞/小时）。然而，在低渗和高渗培养基中，七鳃鳗红细胞中Na⁺内流速率比Li⁺内流速率高约两倍，这是由氨氯吡脒敏感成分的差异决定的。在酸化的七鳃鳗红细胞（细胞内pH 6.0）中，由于氨氯吡脒敏感的Na⁺/H⁺（Li⁺/H⁺）交换机制的激活，Li⁺和Na⁺内流显著增加，尽管Na⁺/H⁺交换的活性远大于Li⁺/H⁺交换的活性。获得的数据证实了关于七鳃鳗红细胞中存在两种氨氯吡脒敏感的Na⁺转运系统的假设。
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