Effects of parenteral testosterone administration on insulin action in perfused hindlimb muscle of female rats.
The effects of 14 days of testosterone (T) administration (1 mg/kg/d) on insulin-regulated phenylalanine release and glucose uptake by perfused hindquarters of intact and ovariectomized (OVX) female rats were studied. Results were compared with control groups that did not receive T. In the absence of exogenous insulin, T treatment significantly suppressed phenylalanine release (an index of net protein degradation) from hindquarters of intact and OVX rats below that of the intact control group (P less than .01). In perfusions containing insulin (100 or 500 microU/mL), phenylalanine efflux from intact and OVX control hindquarters was significantly lower as compared with hindquarters perfused without exogenous insulin (P less than .01). Insulin also reduced the phenylalanine release by T-treated groups to the efflux rates of control rats perfused at the same insulin concentration. Basal glucose uptake by perfused hindquarters was similar in all four treatment groups. In perfusions containing 100 or 500 microU insulin/mL, glucose uptake by hindlimbs of intact and OVX control rats was increased 2.7-fold and 5-fold, respectively, above that observed in perfusions without insulin (P less than .01). T treatment did not alter glucose uptake by perfused hindquarters in the absence or presence of insulin under these experimental conditions. The results of these studies suggest that T has anabolic effects on skeletal muscle that are independent of exogenous insulin action.
Hager
S R
SR
Department of Medicine, Medical College of Wisconsin, Milwaukee 53226.
Kalkhoff
R K
RK
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight / Q000187:drug effects; D004357:Drug Synergism; D005260:Female; D005947:Glucose / Q000378:metabolism; D006614:Hindlimb / Q000378:metabolism; D007263:Infusions, Parenteral; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D009132:Muscles / Q000187:drug effects*; D009994:Osmolar Concentration; D010052:Ovariectomy; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D013739:Testosterone / Q000097:blood / Q000494:pharmacology*
D000596:Amino Acids; D001786:Blood Glucose; D007328:Insulin; D013739:Testosterone; D005947:Glucose