The Involvement of Calcium Transport Systems of the Plasma Membrane in Calcium Exchange in Neurons of the Carassius gibelio Cerebellum

Abstract

We studied the role of Na+/Ca2+ exchanger (NCX) and Ca2+-ATPase of the plasma membrane (РМСА), known to be the most important intracellular systems controlling calcium exchange in cerebellar neurons of a fish species tolerant to hypoxia, Carassius gibelio. In our experiments, we used the corresponding blockers of these transport systems, ions of lithium and lanthanum. The intracellular Ca2+ concentration ([Ca2+] і ) was measured using a calcium-sensitive dye, Fura-2AM, and a microfluorescence technique. We found that neurons of the Carassius cerebellum possess an effective system of cleaning of the cytoplasm from excessive Ca2+, which is provided by both NCX and РМСА functioning in the plasma membrane. Under conditions of the blockade of functioning of РМСА using lanthanum, the basal Ca2+ level in the cells increased, on average, by 31.4% with respect to the control, independently of the duration of test depolarizations. After switching off of the NCX functioning by the replacement of sodium ions in the extracellular solution by lithium ions, the Ca2+ level in the cell increased by 36.6% with respect to the control (also independently of the duration of depolarization). The obtained data indicate that the functioning of РМСА and NCX in Carassius cerebellar neurons significantly influences the intracellular calcium exchange providing the maintenance of an adequate basal Ca2+ level in these neurons.