Studies on the inhibition of brain synaptosomal Na+/K+-ATPase by mercury chloride and methyl mercury chloride.

The effect of mercury chloride (HgCl2) and methyl mercury chloride (MeHg) on brain synaptosomal Na+/K+-ATPase was determined in vitro. It was shown that HgCl2 is a more powerful inhibitor than MeHg. The IC50 were 5 X 10(-7) M for HgCl2 and 2.3 X 10(-6) M for MeHg. A non-competitive type of inhibition was observed with the two mercurials. Removal of contaminating lipids with the non-ionic detergent Lubrol did not affect the inhibition of either mercurial. It is concluded that non-essential lipids do not play a significant role in the inhibitory effect of MeHg and that the potency of these mercurials on to inhibit brain synaptosomal Na+/K+-ATPase largely depends on their capacity to block sulfhydryl groups.