Imitation of glucagon effects on splanchnic hemodynamics and liver function by N6,2'-O-dibutyryl 3',5'-cyclic AMP (DBcAMP) in cats.

Fasting cats anesthetized with chloralose were used for the experiments. DBcAMP infused at a rate of 340 nmol/kg/min increased the gastrointestinal and intrahepatic portal conductances whereas the hepatic arterial conductance was decreased. The hemodynamic responses to portal and systemic venous administration of DBcAMP were identical. In half of the experiments DBcAMP increased the splanchnic ethanol elimination rate and oxygen consumption and in all experiments there was a decrease in the plasma clearance and extraction ratio of Indocyanine Green. No change in bile flow was observed. DBcAMP infused at a rate of 85 nmol/kg/min was without significant effects on either splanchnic hemodynamics or liver metabolism. DBcAMP infused at a rate of 850 nmol/kg/min accentuated the decrease in hepatic arterial conductanc- but was found to decrease the splanchnic ethanol elimination rate and oxygen cownsumption. Infusion of cAMP, AMP and adenosine at a rate of 340 nmol/kg/min were without measurable effects. Based on these results it is concluded that like the metabolic effects also the vascular effects of glucagon are caused by stimulation of specific glucagon receptors which results in an intracellular release of cAMP.