Effects of methylmercury chloride on various cholinergic parameters in vitro.

The effects of methylmercury chloride and other mercury compounds on cholinergic parameters were studied in vitro. Methylmercury chloride (MMC) and phenylmercury acetate inhibited choline acetyltransferase (ChA) with 20 microM of I50, and mercury nitrate (MN) with 100 microM of I50. All the three compounds had little effect on cholinesterase activity. MMC inhibited a high affinity choline uptake with 41 microM of Ki, as well as a low affinity choline uptake with 250 microM of Ki. MMC did not affect a spontaneous and potassium-stimulated ACh release from brain tissue slices incubated in eserinized Krebs-Ringer's solution up to the concentration of 100 microM. It was shown that the organic mercury compounds, such as methylmercury, were potent inhibitors of the choline uptake systems, as well as ChA activity.