Compared to lean controls, morbidly obese subjects showed a significantly lower age- and gender-adjusted UCP mRNA expression level in the intraperitoneal adipose tissue (3.467 +/- 2.483 vs. 6.917 +/- 4.292 amol/fmol beta-actin mRNA; mean +/- SD, P < 0.002), while UCP mRNA abundance in extraperitoneal adipose tissue did not differ between obese and nonobese subjects.