Quantitative analysis of the contribution of hepatic, renal and portal circulation to the clearance of exogenous catecholamines.

The contribution of hepatic, renal and portal circulation to the clearance of exogenous catecholamines was analyzed quantitatively. During infusion of clinical doses of norepinephrine, epinephrine and dopamine in dogs, the plasma level of catecholamine and the plasma flow were measured simultaneously. Percentage of contribution was calculated from the following equation; transorgan difference of plasma catecholamine (ng/ml) x plasma flow (ml/min) x 100/dose (ng/min). This value means the percentage of the amount of catecholamine cleared by an organ to the amount of catecholamine administered into the body. Significant transorgan gradients of plasma levels of norepinephrine, epinephrine and dopamine were observed in each of hepatic, renal and portal circulation. The calculated contribution values indicate that hepatic circulation clears 15.9% of norepinephrine, 24.2% of epinephrine and 9.0% of dopamine administered exogenously. The corresponding figures for renal circulation are 8.7, 22.0 and 9%, and those for portal circulation are 11.5, 21.5 and 10.4%.