Sensitivity difference to hepatotoxicity of cocaine in spontaneously hypertensive and Wistar Kyoto rats.

Experiments were conducted to determine the hepatic damage of cocaine in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) rats in terms of serum glutamic-oxaloacetic transaminase (SGOT) activity, liver weight/body weight ratio and hepatic microsomal enzyme activity, i.e., N-demethylase activity or UDP-glucuronyltransferase (GT) activity. In subacute experiments, 2, 4 and 10 daily cocaine treatments elevated the level of SGOT activity and reduced the liver weight/body weight ratio in SHR rats. The ethylmorphine N-demethylase activity and the cocaine N-demethylase activity in SHR rats were significantly greater (31% and 26%, respectively) than those in WKY rats. Ten daily treatments with cocaine diminished the ethyl morphine N-demethylase activity and the cocaine N-demethylase activity in SHR and WKY rats. However, attenuation of 4-nitrophenol GT activity was only observed in SHR rats. In acute experiments, a single dose of cocaine, 40 mg/kg, elevated the SGOT activity in SHR rats and reduced the 4-nitrophenol GT activity in SHR rats, but it did not affect the activities of SGOT and 4-nitrophenol GT in WKY rats. A higher dose of cocaine, 60 mg/kg, elevated the SGOT activity and reduced cocaine N-demethylase activity and 4-nitrophenol GT activity in both SHR and WKY rats. The present studies suggest that N-demethylation of cocaine plays an important role in the hepatotoxicity of cocaine in animals.