Progressive systolic dysfunction of the heart results in a broad array of physiologic compensatory mechanisms within the kidney. These mechanisms are primarily stimulated by diminution of the effective arterial blood volume and resultant activation of a biochemical cascade of neurohormonal responses, including activation of the renin-angiotensin-aldosterone system and enhanced release of norepinephrine, arginine vasopressin, prostaglandins, endothelin, and atrial natriuretic peptide. The interaction of these neurohormonal systems within the kidney is complex. Vasoconstriction induced by angiotensin II, arginine vasopressin, and catecholamines may decrease renal perfusion by both endocrine and neural actions. In contrast, systemic pressures may rise, which may facilitate perfusion.