Effect of dopamine on renal vessels ?

Ans. is 'a' i.e., Vasodilatation. Injected dopamine produces renal vasodilation, probably by acting on a specific dopaminergic receptor. It also produces vasodilation in the mesentery. Elsewhere; it produces vasoconstriction, probably by releasing norepinephrine, and it has a positive inotropic effect on the hea by an aciton on fliadrenergic receptors. The net effect of moderate doses of dopamine is an increase in systolic pressure and no change in diastolic pressure. Because of these actions, dopamine is useful in the treatment of traumatic and cardiogenic shock.