Adiponectin in the heart and vascular system.

Adipose tissue is not only a storage depot for energy, but also an active endocrine tissue. Adipokines, hormones and cytokines secreted from adipocytes, relay information about energy stores to peripheral tissues throughout the body. Most adipokines are produced in direct proportion to fat mass, and many have proinflammatory or otherwise adverse effects on the cardiovascular system. The notable exception is the cardioprotective adipokine adiponectin, which is secreted in inverse proportion to fat mass. Circulating adiponectin levels are highest in lean individuals and inversely correlate with fat mass. Low levels of serum adiponectin are now appreciated as a risk factor in a variety of cardiovascular diseases including coronary artery disease and restenosis, type 2 diabetes mellitus, and hypertension. In this chapter, we provide an introduction to adiponectin and review the extensive evidence in humans and in mouse and in vitro models for adiponectin's cardioprotective effects.