Time-dependent accumulation of inorganic mercury in subcellular fractions of kidney,liver, and brain of rats exposed to methylmercury

Accumulation of inorganic mercury in subcellular fractions of the kidney, liver, and brain of rats was studied during 48 days after a single injection of 25 mg/kg of methylmercury chloride. The highest ratio of inorganic to total mercury was seen in the cytosol of kidney, 80% of the total being as inorganic mercury at day 48. The ratio in the mitochondria and microsomes of kidney attained a maximum level (about 50% of the total as inorganic) at day 26–37. In the liver, the ratio was strikingly low in the cytosol and microsomes as compared to the light and heavy mitochondria where about 40% of the total was present as inorganic maximally at day 26. The ratio in the brain, determined up to day 15, was very low as compared with the kidney and liver, showing less than 3% of the total in the mitochondria, microsomes, and cytosol, and 5.4% in the myelin fraction. The high accumulation of inorganic mercury in the cytosol of kidney was closely related to metallothionein-like component, while those in the mitochondria and microsomes of kidney and in the mitochondria of liver were exclusively bound to high molecular weight proteins even after deoxycholate treatment.This work was supported in part by a grant from the Japanese Environment Agency and by the Grant-in-Aid for Scientific Research from the Ministry of Education of Japan