Stimulatory Release of Hepatic Lipase Activity from Cultured Rat Hepatocytes by Sodium Orthovanadate : Rapid Increase in Cyclic Adenosine Monophosphate Content

概要

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The release of hepatic triacylglyceride lipase [EC 3.1.1.3] has been examined in isolated hepatocytes in primary culture. The stimulatory release of activity from the hepatocytes into the medium by sodium orthovanadate (vanadate) was observed in a time-and dose-dependent manner. However, insulin failed to have this stimulatory action. Moreover, vanadate rapidly increased the cyclic adenosine monophosphate (cyclic AMP) content in hepatocytes in a time-and dose-dependent manner. The treatment of hepatocytes with H-89,which is a potent cyclic AMP-dependent protein kinase inhibitor, decreased the stimulatory release of hepatic lipase activity by vanadate. The vanadate-stimulated release of the enzyme activity was suppressed by uncouplers. In addition, the incorporation of [^3H] leucine into protein was increased in the presence of vanadate. Under the marked inhibition of protein synthesis by cycloheximide, vanadate still showed a full effect on the release of the enzyme activity. These results suggest that the vanadatestimulated release of hepatic lipase activity from the cultured hepatocytes is associated with a rapid increase in intracellular cyclic AMP content, probably due to an activation of cyclic AMP-dependent protein kinase which requires a metabolic energy process rather than an elevation in enzyme molecule synthesis.
社団法人日本薬学会の論文
1994-05-15