Objective: To evaluate effects of tRA on activity and content of UCP in rat brown adipose tissue mitochondria. Methods: The rats were divided into tRA treatment and control groups using 3H GTP binded UCP in mitochondria. Radioactivity was measured by liquid aglimmer instrument,the dissociation constant( K d)and maximal binding( B max )was determined from Scathard plot. Results: In tRA treatment rat, B max increased by 1.48 fold, K d remained unchanged, rat body weight loss and brown fat weight decreased, white fat became rosiness. Conclusion: tRA can increase concentration of UCP in brown adipose tissue mitochondria, but do not change its activity,it also can increase fat consumption,produce UCP from white adipose tissue. [

AIM: To evaluate the effect of cold acclimation on activity and concentration of UCP in mitochondria inner membrane of rat brown fat. METHODS: Using -labeled GTP binded UCP in mitochondria, radioactivity was measured by liquid aglimmer instrument, the dissociation constand(Kd) and maximal binding(Bmax) were determined by Scatchard plot. RESULTS: In cold acclimation pretreated rats, brown fat weight increased, Bmax increased 1.9-fold,Kd decreased 1.4-fold compared with control. CONCLUSION: Cold acclimation not only increase concentration of UCP in mitochondria inner membrane of rat brown fat,but also increase its activity.