Didn't want to look it up? I'm like that too...
Well, dopamine is a pressor meaning that it supports blood pressure by several mechanisms. You use different pressors (norepi, epi, dobutamine, milrinone, etc.) in different clinical situations.
Dopamine is good for someone with a low cardiac output and low blood pressure (eg: someone with a failing/weak heart who cannot support the BP). At different dosages, it has different effects on the receptors:
1) 1-3 mcg/kg/min: stimulates dopamine receptors primarily and dilates kidney arteries
2) 3-10: beta adrenergic stimulator: increases myocardial contractility and other effects
3) 10-20 both beta and alpha stimulator: increases heart contractility as well as peripheral vasoconstriction (ie: also increases BP)
4) >20: primarily alpha: vasoconstricts
Low dose dopamine, or renal dose dopamine (1-3 mcg) was in the past used to "protect" the kidneys by maintaining blood flow to the kidneys and theoretically increase urine output in a patient who was on other pressors, shock with vasoconstriction, etc. where their kidney arteries would be normally constricted. Well, turns out it doesn't protect the kidneys although you'll still see people use it in that way.
I think people usually use it at doses from 5-15 mcg/kg/min or so...
