Differential effects of methylmercuric chloride and mercuric chloride on the L-glutamate and potassium evoked release of [3H]dopamine from mouse striatal slices.

The effects of CH3HgCl and HgCl2 on the evoked release of 3H from mouse striatal slices prelabelled with [3H]dopamine have been examined. CH3HgCl (10 microM) was observed to increase the L-glutamate-evoked release of [3H]dopamine, while HgCl2 (10 microM) had no effect. In contrast, CH3HgCl at concentrations up to 100 microM had no effect on the 25 mM K+-stimulated release of [3H]dopamine, whereas HgCl2 (100 microM) significantly reduced the 25 mM K+-stimulated release of [3H]dopamine. Thus CH3HgCl and HgCl2 have differential effects on the L-glutamate- and K+-stimulated release of [3H]dopamine from mouse striatal slices, suggesting that these compounds may have different sites and (or) mechanisms of action in altering neurotransmitter release. It is suggested that CH3HgCl may act predominantly at intracellular sites or at the level of the L-glutamate receptor, whereas the major site of action of HgCl2 may be the voltage-operated calcium channel.