Regulation of lipolysis by β-adrenergic activation and exercise in obese African-American and Caucasian women

• Main Author: Raymer, Dustin K
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01.01.2012
• Subjects: Kinesiology; Physiology
• ISBN: 126734024X; 9781267340245

African-American women (AAW) are twice as likely to be obese as Caucasian women (CW); however, previous in-vitro studies have shown that AAW have higher densities of beta-adrenergic receptors (B-AR) in the subcutaneous (SC) adipose tissue and an increased lipolytic response to B-AR stimulation when compared to CW. There are no in-vivo studies to help resolve this apparent contradiction between in-vitro lipolytic response and the incidence of obesity. The purpose of this study is therefore to determine if AAW, as compared to CW, have a larger lipolytic response to pharmacological (isoproterenol) and physiological (exercise) stimulation, Methods: 33 obese women (16 AAW; 17 CW) participated in the microdialysis (MD) study. MD consisted of two probes placed in SC abdominal adipose tissue and perfused with either isoproterenol (ISO) or a control solution. Dialysate glycerol (index of lipolysis) was measured from probes at rest and, from the control probe, during exercise. Results: Dialysate glycerol increased 384.9% in AAW and 191.2% in CW in response to IS0 (p=0.046 AAW vs CW). Dialysate glycerol increased 66 μmol/L in AAW and 84 μmol/L in CW in response to exercise (p=0.94 AAW vs CW). Conclusion: AAW have a higher lipolytic response to pharmacological B-AR stimulation, but have a similar lipolytic response to exercise, as compared to CW. These findings suggest that lipolytic response to B-AR stimulation and exercise are likely not contributing factors to the higher incidence of obesity in AAW as compared to CW.