Effect of fructose on phenylephrine-induced glucose output in perfused rat liver

Glucose output induced by phenylephrine in perfused livers of fed rats was decreased by 34% during an infusion of fructose, but was increased by 30% (compared to controls) following cessation of fructose infusion. Corresponding changes in hepatic inorganic phosphate (Pi) were also observed with a 40% decrease and a 48% increase in Pi concentration being measured during and following fructose infusion, respectively. The data suggest that the glycogenolytic response to phenylephrine is dependent on the hepatic Pi concentration. It is also suggested that enhanced hepatic Pi concentrations and glycogenolytic responses observed following fructose infusion may antagonize insulin-induced suppression of hepatic glucose output and thus play a role in the glucose intolerance and insulin resistance associated with sucrose or fructose feeding.