LIPOPROTEIN-LIPASE AND GLUCOSE-6-PHOSPHATE-DEHYDROGENASE ACTIVITIES IN BOVINE AND OVINE ADIPOSE-TISSUE INCUBATED FOR 7 DAYS - EFFECTS OF INSULIN AND OR DEXAMETHASONE/

The in vitro regulation of lipoprotein lipase (LPL) and glucose-6-phos phate dehydrogenase (G6PDH) activity in bovine and ovine adipose tissu e was investigated. Adult non-lactating non-pregnant cows (n = 5) or e wes (n = 5) were given limited amounts of feed for 8 or 10 days and th en overfed for 10 (ewes) or 21 (cows) days. Perirenal adipose tissue e xplants were incubated for 2, 4 or 7 days. Regardless of the experimen tal conditions, the activity of LPL and G6PDH after 2 days of incubati on was lower than in fresh tissue Insulin significantly increased LPL activity in bovine but not in ovine adipose tissue, and it had no effe ct on G6PDH activity in the two species. Dexamethasone addition to the insulin-supplemented medium significantly increased LPL activity in o vine adipose tissue, whereas it was decreased in bovine adipose tissue on days 4 and 7. Moreover, dexamethasone addition to the insulin-supp lemented medium did not change G6PDH activity in the two species on da y 2, whereas it was increased in bovine and ovine adipose tissue on da ys 4 and 7. Therefore, the effects of insulin and/or dexamethasone on LPL and G6PDH differed with ruminant species and incubation time.