EFFECTS OF SIMULTANEOUS ETHANOL AND TOLUENE EXPOSURE ON NERVE-CELLS MEASURED BY CHANGES IN SYNAPTOSOMAL CALCIUM-UPTAKE AND (CA2+/MG2+)-ATPASE ACTIVITY

The effect of simultaneous exposure of rats to toluene and ethanol on synaptosomal calcium uptake and (Ca2+/Mg2+)-ATPase activity was studied. Rats were exposed to 500 p.p.m. toluene by inhalation for 12 hr a day during four weeks. During the exposure period, the rats had access to 5% sucrose solution containing 20% ethanol or to 5% sucrose solution alone. Rats drinking ethanol exhibited a smaller weight gain than rats drinking water alone. Furthermore, rats exposed simultaneously to toluene and ethanol had a higher ethanol intake than unexposed rats. The toluene exposure caused a higher synaptosomal calcium uptake in vitro. Ethanol intake did not change the synaptosomal calcium uptake in vitro. The synaptosomal calcium uptake in rats exposed to toluene and ethanol was nearly identical to that measured in control rats. In vivo exposure to toluene, or ethanol, or toluene/ethanol simultaneously did not affect the (Ca2+/Mg2+)-ATPase activity in vitro. Incubation with toluene in vitro decreased the (Ca2+/Mg2+)-ATPase activity in a concentration dependent manner. Ethanol had only a slight effect on the enzyme. Simultaneous incubation with toluene and ethanol showed an antagonistic effect of ethanol on the toluene inhibition of the ATPase activity.