PURPOSE: Metabolic Syndrome as defined by ATP III criteria, a constellation of 
risk factors associated with insulin resistance, predisposes to premature 
atherosclerosis and early coronary events. Whether that negative risk profile is 
associated with endothelial dysfunction remains to be established.
MATERIALS AND METHODS: Transcapillary escape rate of albumin (TERalb), a measure 
of capillary permeability and integrity of systemic capillary endothelium, and 
forearm vasodilation to intra-arterial acetylcholine (ACH), an index of nitric 
oxide (NO)-mediated vasomotor dysfunction, were assessed in 24 non-diabetic, 
uncomplicated hypertensive men with Metabolic Syndrome according to ATP III 
criteria (hypertension with at least two additional traits such as high 
triglycerides, low HDL, abdominal obesity, impaired fasting or post-load plasma 
glucose). Twelve age-matched lean normal hypertensive patients with normal lipid 
and glucose profile and nine normotensive subjects were the controls. All 
patients underwent lipids determination and fasting and post-OGTT insulin 
assessment; HOMA-IR was the index of insulin resistance.
RESULTS: TERalb was higher in hypertensive patients with Metabolic Syndrome, 
without differences between hypertensive and normotensive controls. Blood 
pressure (BP), lipids, plasma glucose, insulin levels and HOMA-IR were unrelated 
to TERalb. Responses to acetylcholine were selectively attenuated in metabolic 
patients and, on an individual basis, related only to HDL cholesterol levels, 
independent of LDL cholesterol, BP, body size, triglycerides, and HOMA-IR 
values. No relationship existed between responses to acetylcholine and TERalb.
CONCLUSIONS: Altered systemic capillary permeability characterizes 
insulin-resistant hypertensive patients with Metabolic Syndrome. That defect, 
which may promote early atherosclerosis development, coexists with blunted 
endothelial-mediated vasodilation, indicating a pervasive abnormality of 
endothelial function.