INSULIN AND(OR) DEXAMETHASONE REGULATION OF GLUCOSE AND ACETATE UTILIZATION IN OVINE AND BOVINE ADIPOSE-TISSUE EXPLANTS INCUBATED FOR 7 DAYS

An in vitro system was used to study the regulation of glucose and ace tate utilization by bovine and ovine adipose tissue (AT). Adult nonlac tating, nonpregnant cows (n = 5) and ewes (n = 5) were given limited a mounts of feed for 8 to 10 d, then overfed for 10 (ewes) or 21 (cows) d. Perirenal AT explants were incubated for 7 d. The effect of 2 mU/mL of insulin on glucose utilization was significant in bovine but not i n ovine AT during the Ist d in vitro, whereas the relationship was rev ersed from the 4th d of incubation. The effect of insulin on acetate u tilization was significant in bovine but not in ovine AT. The addition of dexamethasone (DEX, 100 nM) to the insulin-supplemented medium inc reased (P <.05) glucose and acetate utilization by ovine AT. However, DEX did not affect substrate utilization by bovine AT in the presence of insulin. The DEX alone decreased glucose and acetate utilization by bovine and ovine AT during the first 4 d of incubation. So, the effec ts of insulin and(or) DEX on substrate utilization differed with speci es and incubation time.