Comparison of the vasodilator action of dopamine and dopamine agonists in the renal and coronary beds of the dog.

1 The effects of dopamine and the dopamine receptor agonists, SK&F 38393 and bromocriptine, on renal and coronary blood flow in the anaesthetized dog were examined. Dopamine was found to dilate both vascular beds, whereas SK&F 38393 increased renal blood flow but did not have any dilator activity in the coronary vasculature. Bromocriptine did not cause vasodilatation in either vascular bed. 2 The vasodilator responses to dopamine and SK&F 38393 were significantly reduced by the dopamine receptor antagonists, ergometrine or metoclopramide. 3 It is proposed that the selective action of SK&F 38393 on the renal vasculature suggests that the dopamine receptors of the renal and coronary vascular beds may be of different types.