Effects of liver-tumor promoters on phalloidin sensitivity of rat hepatocytes.

Hepatocytes were isolated by a collagenase perfusion method from male F-344 rats fed a diet containing 0.05% phenobarbital (PB), 0.05% dichlorophenyltrichloroethane (DDT), 0.25% ethyl-alpha-p-chlorophenoxyisobutyrate (CPIB), 0.02% methapyrilene hydrochloride (MP), 0.05% amobarbital (AB) or 0.05% diphenylhydantoin (DPH) for 8 weeks. An increase in the incidence of gamma-glutamyltransferase (GGT)-positive hepatocytes was found in rats fed PB or DDT, while CPIB strikingly decreased the incidence. There was no change in the incidence in rats fed MP, AB or DPH. Sensitivity to phalloidin, in terms of formation of multiple cytoplasmic blebs, of the 1-h cultured hepatocytes of rats fed PB, DDT or MP was decreased in both GGT-negative and GGT-positive hepatocytes. The sensitivity of GGT-negative hepatocytes of rats fed CPIB was also decreased. Experiments on phalloidin consumption showed decreases in the hepatocyte toxin uptake of rats fed PB, DDT, CPIB or MP. AB and DPH had no effects on the sensitivity of both GGT-negative and GGT-positive hepatocytes.