title: Differences in the lipolytic function of adipose tissue preparations from Black American and Caucasian women.
abstract: The purpose of this study was to determine the potential causes of the lower lipolytic rates in obese Black American women compared to obese Caucasian women. Subcutaneous and omental adipose tissue were obtained from subjects during abdominal surgery, and hormone-sensitive lipase (HSL) mass, mRNA, and activity were determined. HSL mRNA levels did not differ between the Black American and Caucasian women in either subcutaneous or omental adipose tissue. However, HSL mass was approximately 35% lower (P <.05) in both subcutaneous and omental adipose tissue of the Black Americans. Because of these differences, we measured HSL activity in frozen subcutaneous and omental adipose tissue, and also measured basal and isoproterenol-stimulated lipolytic rates in tissue fragments. No racial differences were found in the activity of HSL in either subcutaneous or omental adipose tissue. However, basal lipolytic rates in the Black Americans were 53% and 44% lower (P <.05) in the subcutaneous and omental fat, respectively, compared to the Caucasian women, despite a lack of difference in cell size between the 2 groups. Interestingly, the degree of stimulation by isoproterenol was higher in both the subcutaneous and omental adipose tissue of the Black American than those of the Caucasian women, resulting in equal stimulation by isoproterenol in the 2 groups. These results indicate that despite the lower mass and lower basal HSL activity in the obese Black American women, stimulation of HSL results in equal activity of the enzyme in the 2 races. This suggests that the signaling pathway of HSL stimulation is more efficient in the Black American women.
authors.affiliation: Department of Biochemistry, East Carolina University, Greenville, NC 27858, USA.
authors.forename: Hisham
authors.initials: H
authors.lastname: Barakat
authors.forename: Robert C
authors.initials: RC
authors.lastname: Hickner
authors.forename: Jonathan
authors.initials: J
authors.lastname: Privette
authors.forename: Joseph
authors.initials: J
authors.lastname: Bower
authors.forename: Enhui
authors.initials: E
authors.lastname: Hao
authors.forename: Vidya
authors.initials: V
authors.lastname: Udupi
authors.forename: Allan
authors.initials: A
authors.lastname: Green
authors.forename: Walter
authors.initials: W
authors.lastname: Pories
authors.forename: Ken
authors.initials: K
authors.lastname: MacDonald
mesh_terms: D017667:Adipocytes / Q000201:enzymology; D000273:Adipose Tissue / Q000187:drug effects / Q000201:enzymology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000328:Adult; D044383:Black People; D005260:Female; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D050356:Lipid Metabolism; D009765:Obesity / Q000201:enzymology / Q000378:metabolism*; D009852:Omentum; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D012867:Skin; D002787:Sterol Esterase / Q000235:genetics / Q000378:metabolism*; D015431:Weight Loss; D044465:White People; D001741:Black or African American
chemical_list: D000318:Adrenergic beta-Agonists; D012333:RNA, Messenger; D002787:Sterol Esterase; D007545:Isoproterenol