CLENBUTEROL-INDUCED INSULIN-RESISTANCE IN CALVES MEASURED BY HYPERINSULINEMIC, EUGLYCEMIC CLAMP TECHNIQUE

Hyperinsulinemic, euglycemic clamp rests were performed on calves befo re and after clenbuterol treatment. Clenbuterol was given as 2 intramu scular injections with an interval of about 12 h. The dose used was 1 mu g/kg b.w. The treatment resulted in increased plasma levels of insu lin and glucose. The results of the clamp tests showed that clenbutero l induced a transient decrease in insulin sensitivity. Both insulin me diated glucose disposal (M), expressed as mu mol/kg live b.w./min. and the Mil-index (M divided by the average insulin concentration at stea dy state) were significantly reduced after treatment. The effect of cl enbuterol on carbohydrate metabolism seemed to be rather short-lived s ince significant changes occurred only in animals treated 5-6 h prior to the test. According to the literature, the metabolic effects of cle nbuterol have been studied only after the high doses used for growth p romoting purposes. The results from the present study showed that simi lar changes occur also after doses at the therapeutic level. The hyper insulinemic, euglycemic clamp test was considered to be a valuable too l for the study of insulin sensitivity in cattle.