Exogenous ATP and carbohydrate metabolism in the rat liver

The present study analyzed the actions of exogenous ATP on liver carbohydrate metabolism by using both isolated perfused rat livers and hepatocytes as model systems. The metabolic parameters measured in the perfused livers were glucose production, lactate production, oxygen consumption, and K+ movement. All parameters were monitored continuously during the perfusions in order to assess transient effects. ATP increased both glucose and lactate production in the isolated rat liver when perfused with either constant pressure or constant flow. ATP increased oxygen consumption in the perfused liver at a low concentration (10 microM) but was inhibitory at high concentrations (40 and 160 microM). ATP also increased K+ efflux in the isolated perfused liver. ATP did not alter basal glucose production in isolated hepatocytes; however, it did inhibit glucagon-stimulated glucose output by hepatocytes. ATP inhibited lactate production in the isolated hepatocytes. Extracellular ATP has the potential to modify basal as well as hormonal modulation of hepatic carbohydrate metabolism during shock.