INCREASE IN LIPOPROTEIN-LIPASE ACTIVITY IN ISOLATED RAT ADIPOSE-TISSUE BY SELENATE

Sodium selenate (selenate), as well as insulin, increased the lipoprotein lipase (LPL) activity in isolated rat fat pads in a time- and dose-dependent manner. The increase effect of selenate was not additive to that of insulin. The action of selenate and insulin was decreased by amiloride and disappeared when Ca2+ was omitted from the incubation medium. Loading of a chelator of intracellular Ca2+ to the fat pads also greatly inhibited the action of selenate. The maximal increase in inositol 1,4,5-trisphosphate (IP3) content was observed with a 30-s incubation of the fat pads with selenate. Dibutyryl cyclic AMP, 3-isobutyl-1-methylxanthine, carbonyl cyanide m-chlorophenylhydrazone, tunicamycin, and monensin all inhibited the increase effect of selenate on the LPL activity to various extents. These results suggest that selenate increases the LPL activity via amiloride- and monensin-sensitive processes, involving the Ca2+ mobilization linked to a rapid increase in the IP3 content in fat pads.