Different dosages of dopamine can produce different clinical effects. The effects of agonizing sympathetic adrenergic receptors and dopamine receptors in the kidney, mesenteric, coronary arteries and cerebral arteries are dose-dependent. 1. Small doses (0.5-2ug/kg per minute by body weight) mainly act on dopamine receptors, causing vasodilation of kidney and mesenteric vessels, increasing renal blood flow and glomerular filtration rate, and increasing urine volume and sodium excretion. 2. It can directly agonize β1 receptor and indirectly induce the release of norepinephrine from storage site, which can produce positive stress effect on myocardium and increase myocardial contractility and heart beat volume, and finally increase cardiac blood output, systolic blood pressure, pulse pressure, and diastolic blood pressure, with no change or mild increase in total peripheral resistance. The total peripheral resistance is often unchanged, and the coronary blood flow and oxygen consumption are improved; 3. At high doses (>10ug/kg per minute by body weight), α receptors are agonized, resulting in increased peripheral vascular resistance, renal vasoconstriction, and decreased renal blood flow and urine volume. Due to the increase of cardiac blood displacement and peripheral vascular resistance, the systolic and diastolic blood pressure are increased.