Determination of body fat distribution by dual-energy X-ray absorptiometry and attenuation of visceral fat vasoconstriction by enalapril.

Use of dual-energy X-ray absorptiometry (DEXA) data to calculate the percent of body fat in the visceral (%VF) and subcutaneous (%SF) compartments and the mechanism of visceral fat vasoconstriction when intestinal mucosal afferent nerves are stimulated has not been reported. The aim of this study was to compare visceral fat weight determined by DEXA and direct weighing and determine whether enalapril attenuates visceral fat vasoconstriction induced by stimulation of intestinal mucosal afferent nerves. We performed two studies. Study 1: In euthanized mice, DEXA scans were obtained before and after visceral fat dissection. The dissected fat weight was determined by DEXA (VF) and by direct weighing. Study 2: In anesthetized rat preparations, visceral (mesenteric) fat blood flow was monitored by laser Doppler flowmetry (LDF). After baseline, vehicle or 3 mg/kg enalapril (angiotensin-converting enzyme inhibitor) was administered intravenously, followed by 2 ml/kg of 640 microm capsaicin intraduodenally. In study 1, there was agreement between visceral fat weight determined by the DEXA (y) and direct weighing (x): y = 0.98x, r = 0.99, n = 10. In study 2, LDF signals showed an instantaneous decline when capsaicin was administered into the duodenal lumen. After enalapril treatment, the reductions were significantly attenuated compared with those after vehicle treatment. DEXA results combined with visceral fat dissection permit determination of body fat distribution. The instantaneous decline in visceral fat blood flow suggests that the reduction is a neural- rather than a hormone-mediated event, and attenuation by enalapril suggests angiotensin II plays a role.