Metallothionein concentrations and organ retention of mercury in the liver and kidney of the neonatal guinea pig after exposure to mercury vapor.

Neonatal guinea pigs were exposed to mercury vapor on the day of birth, and the following mercury distribution and concentrations of metallothioneins (MTs) in the liver and kidney were observed. In the liver, two hours after exposure, an appreciable amount of mercury accumulated and a substantial portion of this was associated with MTs. During postnatal development, the mercury concentration increased, whereas the hepatic concentration of MTs decreased. The mercury in the soluble fraction of the liver shifted from the region of MTs to the high-molecular-weight region and, finally, the mercury peak in the MT region was not detected. The kidney mercury concentration was high even 2 hr after the exposure and on days 3 and 7 postpartum. The peak concentration was observed on day 3 postpartum. The mean renal concentration of MTs in the mercury-exposed neonates was significantly higher than that of the control at all times observed. The changes in both the mercury level and the concentration of MTs were strongly correlated. Furthermore, most mercury in the soluble fraction was associated with MTs on day 7. These findings indicated enhanced synthesis of MTs in the kidney, but not in the liver, after mercury vapor exposure in the neonatal period, with corresponding elevated copper and zinc concentrations in the kidney.