Bouron A, Reuter H
Department of Pharmacology, University of Bern, Switzerland.
Neuron. 1996 Nov;17(5):969-78. doi: 10.1016/s0896-6273(00)80227-5.
Propagation of action potentials in axons and dendrites increases intracellular Na+ ([Na+]i) and Ca2+ concentrations ([Ca2+]i). While the importance of [Ca2+]i in synaptic transmission is well established, a possible functional role of [Na+]i is unclear. In cultured hippocampal cells, [Na+]i was increased by veratridine. We have then measured spontaneous excitatory postsynaptic currents (sEPSCs) and, by means of fluorescent dyes, changes in [Na+]i, in [Ca2+]i, and in the turnover of the vesicular pool of individual boutons. An elevation of [Na+]i and a concomitant rise in [Ca2+]i, led to a large increase in sEPSC frequency and in the turnover of the presynaptic vesicular pool. Extracellular Ca2+ was essential for these effects of elevated [Na+]i on synaptic transmission. They probably occur via Na+/Ca2+ exchange.
动作电位在轴突和树突中的传播会增加细胞内钠离子（[Na⁺]i）和钙离子浓度（[Ca²⁺]i）。虽然[Ca²⁺]i在突触传递中的重要性已得到充分证实，但[Na⁺]i可能的功能作用尚不清楚。在培养的海马细胞中，藜芦碱可使[Na⁺]i升高。然后我们测量了自发兴奋性突触后电流（sEPSCs），并通过荧光染料测量了[Na⁺]i、[Ca²⁺]i的变化以及单个突触小体囊泡池的周转情况。[Na⁺]i的升高以及随之而来的[Ca²⁺]i的升高，导致sEPSC频率和突触前囊泡池周转大幅增加。细胞外钙离子对于[Na⁺]i升高对突触传递的这些作用至关重要。它们可能通过钠/钙交换发生。
