Metabolic extraction of dopamine in the canine lungs.

Pulmonary metabolism has been demonstrated to be one of the mechanisms of intrapulmonary removal of dopamine. After a bolus injection of [14C]dopamine into the caval vein of an anaesthetized dog a removal of [14C]-radioactivity into the extravascular space was accompanied by an intravascular alteration of the composition of the [14C]compounds during a single transpulmonary passage. A removal of 22% of [14C]-radioactivity out of the bloodstream, together with a metabolic conversion of the remaining [14C]dopamine within the bloodstream, resulted in a total pulmonary extraction of 22% + (0.78 x 18%) = 36%. This report gives a design for further investigation of the metabolic function of the lung sustained by a scheme for problem solving. Also perspectives for clinical application have been compiled.