Tissue specific activation of the endothelin system in severe acute liver failure

The endothelin system has been implicated in the pathogenesis of acute liver failure. However, it has not yet been assessed in a tissue specific manner. - Acute liver failure was induced in rats by two intraperitoneal injections of galactosamine (1.3 g/kg, interval of 12 hours, n = 20). The animals were sacrificed after 48 hours. - Plasma measurements demonstrated that animals receiving galactosamine had a laboratory constellation of severe liver injury and they histologically presented with hepatic necrosis and inflammation. Plasma concentrations of endothelin-1 were elevated 60-fold in the animals receiving galactosamine (p = 0.005). In contrast endothelin-1 tissue contents were decreased in the kidneys and unchanged in the liver. Western blot analysis showed that animals receiving galactosamine had a significantly lower endothelin B receptor concentration in liver and kidney tissue, whereas no differences were detected for endothelin A receptors. - This study demonstrates that the local endothelin system of liver and kidneys is not responsible for the increase of plasma endothelin-1 concentrations in acute liver failure. Since it is well established that the endothelin B receptor acts as a clearance receptor, its decreased density might contribute to the strongly elevated plasma endothelin-1 concentrations seen in this model of acute liver injury.