Stimulatory release of hepatic lipase activity from rat hepatocytes by ruthenium red.
Ruthenium Red (RuR; ruthenium oxychloride ammoniated) stimulated the release of hepatic lipase (HTGL) activity from primary cultured rat hepatocytes into medium in a time- and dose-dependent manner. The RuR-stimulated release of HTGL activity was suppressed by tyrosine kinase (TK) inhibitors (ST-638 and biochanin A). The activity of partially purified TK preparation from hepatocytes was found to be increased by incubation with RuR. In addition, treatment of the hepatocytes with H-89, a potent inhibitor of cAMP-dependent protein kinase (PKA), decreased the stimulatory release of HTGL activity by RuR. Moreover, cAMP content in RuR-incubated hepatocytes was rapidly increased, and activation of PKA was observed. The RuR-stimulated release of HTGL activity is also inhibited by uncouplers and glycosylation inhibitors. In addition, incorporation of [3H]leucine into protein was increased in the present of RuR. Under marked inhibition of protein synthesis by cycloheximide, RuR still showed a full effect on the release of HTGL activity. These results suggest that RuR stimulates the release of HTGL activity through mechanisms of action involving TK- and PKA-activating pathways, which require a metabolic energy-sensitive process rather than elevation of enzyme molecule synthesis.
Morita
T
T
2nd Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Higashimura, Japan. morita@fupham.fukuyama-u.ac.jp
Fujiwara
A
A
Ueki
H
H
Kanagawa
A
A
D000818:Animals; D004396:Coloring Agents / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004734:Energy Metabolism; D006031:Glycosylation / Q000187:drug effects; D007930:Leucine / Q000378:metabolism; D008049:Lipase / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012430:Ruthenium Red / Q000494:pharmacology*; D014316:Tritium
D004396:Coloring Agents; D014316:Tritium; D012430:Ruthenium Red; D011505:Protein-Tyrosine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D008049:Lipase; D007930:Leucine