Body fat and sympathetic nerve activity.

Scherrer U, Owlya R, Lepori M

Department of Internal Medicine B, Centre Hospitalier, Universitaire Vaudois,
Lausanne, Switzerland.

Obesity, a major health problem in industrialized societies, is associated with
a high incidence of cardiovascular complications such as hypertension, ischemic
heart disease and stroke. However, the underlying mechanism relating obesity
and these cardiovascular events is not clear. In lean subjects even slight
elevations in plasma insulin concentration exert marked effects on the
cardiovascular system, and these effects are directly related to insulin
(rather than to insulin-induced stimulation of intermediary metabolism).
Moreover, insulin's vascular effects are mediated both by the sympathetic
nervous system and the L-arginine nitric oxide pathway. Obesity is
characterized by sustained sympathetic activation (possibly related to chronic
hyperinsulinemia) and an impaired vasodilator responsiveness to insulin.
Although, undoubtedly many factors contribute to the increased incidence of
cardiovascular 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--contribute
to sustained elevation of arterial pressure.