DECREASED PERIPHERAL-BLOOD FLOW IN THE PATHOGENESIS OF THE METABOLIC SYNDROME COMPRISING HYPERTENSION, HYPERLIPIDEMIA, AND HYPERINSULINEMIA

Major cardiovascular risk factors, such as hypertension, hyperlipidemia, and diabetes, often cluster in the same individuals. It has been claimed that obesity, hyperinsulinemia, insulin resistance, and a deranged intracellular handling of ions have pathogenetic importance in the development of this metabolic syndrome. However, a decrease in peripheral blood flow is another factor found in all the different facets of this syndrome. An increased peripheral resistance and a rarefaction of skeletal vessels are often seen in hypertensive subjects. Also, the insulin resistance so commonly seen in hypertension may be a consequence of a decreased blood flow because insulin resistance is associated with a decreased capillarization in skeletal muscle. Furthermore, the activity of skeletal muscle lipoprotein lipase, the key enzyme involved in the removal of triglycerides from the circulation, is known to be related to skeletal muscle vascularization. Because enhanced sympathetic activity has been associated with vascular hypertrophy and rarefaction of vascularization, overactivity in this part of the autonomic nervous system may lead to structural changes that will decrease the blood flow in peripheral tissues and thereby induce the metabolic syndrome of cardiovascular risk factors, particularly in individuals who, for genetic reasons, have decreased capillarization at the onset.