Influence of ethnicity and adipose tissue distribution in the regulation of triglyceride turnover and glucose metabolism in omental and subcutaneous adipocytes from obese women

Excess body fat in obesity, particularly when located in the visceral area, has been associated with metabolic abnormalities including systemic insulin resistance and dyslipidemia. The severity of some obesity-related metabolic abnormalities such as hypertriglyceridemia is less in African-American (black) relative to Caucasian (white) women. The magnitude of visceral obesity, independently of total fatness, is associated with the degree of systemic insulin resistance in both races. These metabolic abnormalities are thought to be exacerbated by increased nonesterified fatty acid turnover. The cellular mechanisms underlying increased nonesterified fatty acid turnover in obesity are not well understood, nor have any previous studies examined the regulation of adipocyte lipolysis by insulin as a function of visceral adiposity. Therefore, the objective of this work was to compare the action of insulin on lipid metabolism in adipocytes from black and white women with varying levels of visceral obesity.;The first study showed that the degree of visceral obesity was positively correlated with basal lipolysis, and was negatively correlated with sensitivity to the antilipolytic effect of insulin, in subcutaneous (abdominal and gluteal) adipocytes. These relationships were similar in both races. Since lipolytic flux specifically from visceral fat has been implicated in metabolic disorders, the second study examined lipid turnover in visceral (omental) adipocytes from obese black women. Basal lipolysis, sensitivity to the antilipolytic effect of insulin, glucose conversion to total lipid, and lipoprotein lipase activity were significantly decreased in omental relative to subcutaneous abdominal adipocytes, comparable to data previously reported in obese Caucasian women.;In conclusion, adipocyte insulin resistance may contribute to elevated lipolytic flux in visceral obesity to a similar degree in black and white women.