Differential toxicity of an inhibitor of mitochondrial respiration in canine hepatocytes and adrenocortical cell cultures

Abstract

PD132301-2, a novel inhibitor of acyl-CoA: cholesterol acyltransferase, was previously shown to be an inhibitor of mitochondrial respiration and an adrenal toxicant in several species. To investigate potential mechanisms of tissue-specific toxicity in vivo, dog adrenocortical and hepatocyte cell cultures were exposed to 0.01–30 μm PD132301-2 for 0–24 hr. Cell viability was assessed by neutral red uptake or release assays. Cytotoxicity was observed in adrenocortical cells at 0.01 μ m or above after 2hr of exposure, while 30 μm was not toxic to hepatocytes after 24 hr of exposure. Decreases in adrenocortical cell viability were attenuated in the presence of 20 m m fructose, a glycolytic substrate, and fructose protection was in turn blocked by the glycolytic inhibitor NaF (1 m m). In contrast, PD132301-2-induced hepatocellular toxicity was evident only following pretreatment with NaF or metyrapone, a broad-spectrum cytochrome P-450 inhibitor. With either co-treatment, hepatocyte viability was reduced 50% after 6 hr at 1 μ m or more PD132301-2. These data indicate that the relative sensitivity of adrenocortical cells to the cytotoxic effects of PD132301-2 may be due, in part, to their relative lack of the metabolic detoxification and glycolytic reserve capacities that appear to protect hepatocytes from PD132301-2 toxicity.