BODY-FAT AND SYMPATHETIC-NERVE ACTIVITY

Obesity, a major health problem in industrialized societies, is associ ated with a high incidence of cardiovascular complications such as hyp ertension, ischemic heart disease and stroke. However, the underlying mechanism relating obesity and these cardiovascular events is not clea r. In lean subjects even slight elevations in plasma insulin concentra tion exert marked effects on the cardiovascular system, and these effe cts are directly related to insulin (rather than to insulin-induced st imulation of intermediary metabolism). Moreover, insulin's vascular ef fects are mediated both by the sympathetic nervous system and the L-ar ginine nitric oxide pathway. Obesity is characterized by sustained sym pathetic activation (possibly related to chronic hyperinsulinemia) and an impaired vasodilator responsiveness to insulin. Although, undoubte dly many factors contribute to the increased incidence of cardiovascul ar complications in overweight subjects, sympathetic activation could be one important mechanism and either trigger acute events or-possibly in conjunction with an impairment in insulin-induced vasodilation-con tribute to sustained elevation of arterial pressure.