Cyclosporine A-induced acute hepatotoxicity in guinea pigs is associated with endothelin-mediated decrease in local hepatic blood flow.

AIMS: To bring further insight into the mechanism of cyclosporine A (CsA)-induced hepatotoxicity, the acute effect of CsA on local hepatic blood flow (LHBF) and its association with systemic hemodynamics, histopathological and biochemical indicators of liver toxicity were studied in guinea pigs in vivo. The association of endothelin (ET) and/or Cremophor-EL (C-EL, vehicle in parenteral CsA preparation) with CsA effects was also investigated. MAIN METHODS: Animals were assigned into five groups; control, CsA, C-EL, Bosentan (non-selective ET receptor antagonist)+CsA, and BQ-123 (ET(A) receptor antagonist)+CsA. CsA was infused intravenously (i.v.) at 20 and 10mg/kg doses by 15 min interval. Antagonists were administered 15 min before CsA infusion. LHBF and mean arterial blood pressure (MAP) changes were simultaneously recorded. Blood and liver samples were collected for biochemical and histopathological examinations. KEY FINDINGS: CsA, but not C-EL, decreased LHBF by 53.3% at the end of 30 min. Although being non-significant, CsA slightly increased MAP suggesting that, CsA-induced acute decrease in LHBF was likely independent of MAP changes. Bosentan (5mg/kg, i.v.) and BQ-123 (1mg/kg, i.v.) pre-treatments prevented the CsA-induced decrease in LHBF suggesting that CsA decreases LHBF through an ET-related mechanism. Additionally, CsA, but not its vehicle C-EL, caused marked acute pathological changes in the liver morphology. SIGNIFICANCE: CsA-induced findings of acute hepatotoxicity were prevented by bosentan and BQ-123 pre-treatments. Thus, CsA seems to exert acute hepatotoxic effect through ET-related mechanisms.