Context: African American women (AAW) lose less weight and at a slower rate than Caucasian women (CAW) under the same weight-loss regimens. A potential cause of this finding is inhibition of lipolysis.

Objective: Since -2 and adenosine receptors are directly involved in inhibition of lipolysis, differences in -2 or adenosine A1 receptors in visceral adipose tissue (VAT) and sc adipose tissue (SAT) from obese AAW and CAW were determined.

Design: Measurement of Bmax of -2 and adenosine A1 receptors as well as protein and mRNA levels of the adenosine receptor in VAT and SAT from AAW and CAW.

Setting: General Community.

Patients: Patients selected by Body Mass Index >40 and age matched.

Main Outcome Measures: Bmax (density) of the two receptors, and protein and mRNA levels of adenosine receptors were determined in adipose tissue of AAW and CAW.

Results: No differences were found in -2 receptor Bmax in either VAT or SAT from AAW and CAW. Bmax (but not Kd) for the adenosine A1 receptor in VAT from AAW was higher (P < 0.05) than in VAT from CAW. Adenosine receptor protein and mRNA levels were significantly higher in VAT from AAW than in VAT from CAW. No racial differences in these parameters were observed in SAT.

Conclusions: These data suggest that inhibition of lipolysis by adenosine has the potential to be greater in obese AAW and this could possibly be one explanation for the observation that obese AAW have a more difficulty in loosing weight than obese CAW.