CHF: circulatory homeostasis gone awry

The role of the renin-angiotensin-aldosterone system (RAAS) is integral to salt and water retention, particularly by the kidneys. Over time, positive sodium balance leads first to intra- and then to extravascular volume expansion, with subsequent symptomatic heart failure. This report examines the role of the RAAS in regulating a less well recognized component essential to circulatory homeostasis--central blood volume. The regulation of central blood volume draws on integrative cardiorenal physiology and a key role played by the RAAS in its regulation. In presenting insights into the role of the RAAS in regulating central blood volume, this review also addresses other sodium-retaining states with a predisposition to edema formation, such as cirrhosis and nephrosis.