Nd3+ influx mediated by the Na+ /Ca2+ exchange in human lymphocytes

A series of experiments on Nd3+ influx mediated by the Na+/Ca2+ exchange in human lymphocytes were processed by fura-2 method. The results show that when the cellular Na+ gradient is reversed, Nd3+ can enter the lymphocytes and voltage dependent calcium channels are not responsible for Nd3+ influx. It suggests that the Na+ / Ca2+ exchange provides a major route for NP entry in human lymphocytes. Intracellular free Nd3+ concentrations ([Nd3+ ](i)) are directly proportional to extracellular free Nd3+ concentrations ([Nd3+ ](i)) and the maximum [Nd3+](i) is (3.67 +/- 0.32) X 10(-14) mol . L-1 . [Nd3+ ](i) decreases with decreasing extracellular pH but increases with decreasing intracellular [ Ca2+](i) The Ca2+ influx and Nd3+ influx mediated by the Na+/Ca2+ exchange might be mutually competitive. Furthermore, the results also suggest that cytosolic Nd3+ is transported by the ATP-dependent Ca2+ pump and intracellular Nd3+ appears to be taken up by endoplasmic reticulum and not be significantly accumulated by niitochondria.