Effects on mitochondrial metabolism in livers of guinea pigs after a single or repeated injection of As2O3.

Abstract

Differences in the metabolite pattern were observed in previous experiments in guinea pig livers after a single injection or prolonged (5 days) treatment with AS2O3 (Reichl et al. 1988). To elucidate the underlying mechanism the effect of As2O3 on liver metabolism was therefore investigated. Male guinea pigs received either a single dose (s.d.) of As2O3 10 mg x kg-1 s.c. or repeated doses (r.d.) of 2.5 mg x kg-1b.i.d. on 5 consecutive days. One hour after the s.d. or 1 h and 16 h after the last injection in the r.d. groups the animals were sacrificed in anaesthesia. The livers were removed by freeze clamping for the determination of various metabolites. In the s.d. group a significant decrease in hydroxybutyrate, acetylCoA, adenosinemonophosphate and in the ratio of hydroxybutyrate/acetoacetate and an increase in pyruvate, citrate, malate, and adenosinetriphosphate were observed. A significant decrease in glycogen, pyruvate, alpha-ketoglutarate, acetylCoA, and acetoacetate and a significant increase in malate and in the ratios of lactate/pyruvate and hydroxybutyrate/acetoacetate were observed in the r.d.1-h group. In the r.d.16-h group a significant decrease in glycogen, pyruvate, lactate, and adenosinemonophosphate was found, but the values tended towards control values. The data are consistent with mechanisms of As2O3 toxicity in other species as PDH inhibition with consecutive citric acid cycle and gluconeogenesis inhibition and excessive carbohydrate depletion.