Pulmonary extraction of dopamine in the conscious dog

Thus far non-respiratory pulmonary functions have mainly been studied in isolated lungs or in intact anaesthetized animals. Therefore, we studied pulmonary handling of vasoactive hormones in the conscious dog. Dopamine, adrenaline and noradrenaline (3 nmol/ml) were injected together with cardiogreen (4 mg/ml) into the caval vein during 5, 10 and 15 s in three separate experiments. Indicator-dilution curves were derived from samples originating from the pulmonary artery and the aorta. During a single passage of the lung dopamine was removed to the greatest extent, noradrenaline somewhat less, and adrenaline not at all, irrespective of the injection duration. In particular, the extraction of dopamine, which was not emphasized in literature, was a remarkable finding.