THE IMPAIRMENT OF FLOW-MEDIATED VASODILATATION IN OBESE MEN WITH VISCERAL FAT ACCUMULATION

BACKGROUND: Obesity has been reported to be associated with coronary a rtery disease and other atherosclerotic diseases. Recently, evidence h as accumulated indicating that intra-abdominal visceral fat accumulati on contributes to atherogenesis; however, the mechanism underlying thi s remains to be determined. This study was undertaken to elucidate whe ther intra-abdominal visceral fat accumulation impairs vascular endoth elial function in obese men. METHODS AND RESULTS: Thirty-eight obese m en (body mass index (BMI) greater than or equal to 26.0), aged 19-64 y (mean age 37.6 +/- 1.8 y) and 23 age-matched non-obese subjects were examined. According to the ratio of the maximum thickness of preperito neal fat to the minimum thickness of subcutaneous fat (Pmax/Smin) obta ined by longitudinal ultrasound scanning in the subxiphoid region in o bese men, we divided obese subjects into two categories; visceral (Pma x/Smin greater than or equal to 1; n = 23) and subcutaneous type (Pmax /Smin (1; n = 15). To investigate endothelial function, we performed u ltrasound measurement of the brachial artery diameter non-invasively b oth at rest and during reactive hyperaemia in the muscle distal to the brachial artery which causes endothelium-dependent vasodilatation. Th e brachial diameter change was also measured after sublingual administ ration of nitroglycerin, which causes endothelium-independent vasodila tation. Flow-mediated diameter (D) increase (%FMD; Delta D/D x 100), i n the subjects with visceral type obesity (3.09 +/- 0.43%) was signifi cantly lower than those of the subjects with subcutaneous type obesity and non-obese subjects (7.90 +/- 0.51%, 8.91 +/- 0.44%, respectively, P < 0.01), The magnitude of endothelium-independent vasodilatation by nitroglycerin was similar in all groups. On multiple regression analy sis, the Pmax/Smin showed a significant inverse correlation with %FMD. CONCLUSIONS: The subjects with visceral type obesity, rather than tho se with the subcutaneous type, are associated with impaired flow-media ted endothelium-dependent vasodilatation of the brachial artery.