MOVEMENT OF RADIOACTIVE CALCIUM IN BRAIN SLICES AND INFLUENCES ON IT OF PROTOVERATRINE, OUABAIN, POTASSIUM CHLORIDE AND COCAINE

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Abstract
The movement of Ca45 in brain cortex slices of guinea pigs and the influences on it of protoveratrine, ouabain, KC1 and cocaine were examined. The following results were obtained. Addition of azide and omission of glucose resulted in an increase in Ca45 -influx. This increase in Ca45 -influx caused by depression of the metabolism was not significantly influenced by addition of cocaine. Protoveratrine, ouabain or a high concentration of KCl caused an increase in Ca45-influx into brain slices. The increase caused by protoveratrine and ouabain was completely blocked by cocaine while that by KC1 was partially blocked. Efflux of Ca45 from brain slices was reduced by replacing normal Ringer by Ca-free Ringer containing EDTA [ethylene diamine tetra acetic acid]. There was an increase in Ca45-efflux from brain slices on addition of protoveratrine, ouabain, KC1 or azide both in normal Ringer and in Ca-free Ringer. Cocaine largely prevented the increased efflux of Ca45 caused by protoveratrine and ouabain, but the increased efflux of C45 caused by KCl was only partially inhibited and that by azide did not seem to be affected significantly by addition of cocaine. The role of Ca in membrane permeability and the action mechanisms of these drugs are discussed on the basis of these findings.