Sodium Orthovanadate Increases Phospholipase A_2 Activity in Isolated Rat Fat Pads : a Role of Phospholipase A_2 in the Vanadate-Stimulated Release of Lipoprotein Lipase Activity

概要

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Phospholipase (PL) A_2 activity prepared from isolated rat fat pads incubated with sodium orthovanadate (vanadate) was increased in a time-and dose-dependent manner. The increasing effect of vanadate was reduced in the presence of tyrosine kinase inhibitors. Under the inhibition of protein synthesis by cycloheximide, vanadate still showed a full effect on the increase in PL A_2 activity. Various PL A_2 inhibitors, such as manoalide, quinacrine and p-bromophenacyl bromide, suppressed the stimulatory release of lipoprotein lipase (LPL) activity from the fat pads by vanadate. Moreover, the vanadate-stimulated release of LPL activity was decreased by the cyclooxygenase and thromboxane synthetase inhibitors, and a thromboxane A_2 receptor antagonist, but was never suppressed by a lipooxygenase inhibitor. The stimulatory release of LPL activity by vanadate was also decreased in the presence of tyrosine kinase inhibitors. These results suggest that vanadate increases PL A_2 activity, and the increase in PL A_2 activity is partly involved in the vanadate-stimulated release of LPL activity with an association to the membrane tyrosine kinase.
公益社団法人日本薬学会の論文
1995-02-15