The effects of dopamine are dependent on the dose infused. Dopamine was used widely at low doses in an attempt to secure preferential DA1 stimulation and increase renal perfusion; however, a large multicentre randomised controlled study comparing 'renal dose' dopamine and diuretics showed no difference in the incidence of renal failure. The widespread use of low dose dopamine (<3pg/kg/min) has thus diminished considerably in recent years. Higher doses increase cardiac contractility via p1 stimulation and produce vasoconstriction via a stimulation. Where vasoconstriction is inappropriate this will reduce renal perfusion. There is, however, evidence of natriuresis and diuresis by enhanced Na+ transport in the ascending loop of Henle. This effect is similar to that of a loop diuretic. In addition to the renal effects of DA1 stimulation there may be preferential perfusion of the splanchnic bed, though any benefits to patients have yet to be shown.

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