Endothelial nitric oxide synthase content in adipose tissue from obese and lean African American and white American women

Abstract

It has been demonstrated that the enzyme endothelial nitric oxide synthase (eNOS) is present in adipose tissue, resulting in nitric oxide production and subsequent inhibition of lipolysis. A higher eNOS content has also been reported in the subcutaneous abdominal adipose tissue of obese than in that of lean white men. Furthermore, a lower lipolytic rate in obese than in lean women and a lower lipolytic rate in African American (AA) than in white American (WA) women have been demonstrated. The purpose of this study was to determine if eNOS protein content is higher in the subcutaneous and omental adipose tissues of obese than in those of lean women and if eNOS protein content is higher in the subcutaneous and omental adipose tissues of AA than in those of WA women. Whole tissue homogenates were prepared from frozen omental and subcutaneous adipose tissue samples obtained from lean and obese and AA and WA elective abdominal surgery patients and were analyzed for eNOS protein content using enzyme-linked immunosorbent assay. The adipose tissue eNOS protein content was approximately 40% higher in obese than in lean individuals (omental, 326.9 ± 40.5 pg/mL lean and 445.3 ± 38.0 pg/mL obese; subcutaneous, 246.8 ± 20.8 pg/mL lean and 343.1 ± 19.0 pg/mL obese; P < .05). There was no difference between the races for eNOS protein content in omental adipose tissue. In subcutaneous adipose tissue, there was a higher eNOS content in obese (417.1 ± 78.9 pg/mg total protein) than in lean (216.7 ± 29.9 pg/mg total protein) ( P < .05) WA women, but there was no difference in subcutaneous adipose eNOS content between obese and lean AA women (250.7 ± 47.4 and 294.1 ± 42.2 pg/mg total protein, respectively). The higher eNOS content in the adipose tissue of obese than in that of lean WA women in the fasted state may contribute to the reduced lipolytic activity in WA women; however, eNOS protein content probably does not contribute to differences in lipolytic rates between AA and WA women.