Effect of dopamine on the isolated perfused lung lobes of the dog.

Dopamine (beta-3:4-dihydroxyphenylethylamine) has a pressor action on the pulmonary vascular bed in isolated perfused lung lobes of the dog. Its pulmonary vasoconstrictor effect in this preparation is about 1/20-1/30 that of adrenaline or noradrenaline. When compared with adrenaline, dopamine is less effective as a vasoconstrictor in the bronchial vascular system than in the pulmonary circulation. Even very large doses of dopamine had no bronchomotor effect in the isolated perfused lung lobes. Addition of dopamine alone, or of dopamine together with some "new" blood, sometimes caused a potentiation of the pulmonary vasoconstrictor responses to sympathetic nerve stimulation.