Isoproterenol produces a rapid increase in sialidase activity in rat heart tissue and cardiomyocyte-derived H9c2 cells in culture.
The effects of isoproterenol on sialidase activity in rat cardiomyocytes were examined. Administration of isoproterenol to rats (0.2 or 2 mg/kg body weight) produced an increase in sialidase activity in total membrane fraction of heart tissue within 120 min (121+/-13% of the control at 120 min after administration of 0.2 mg isoproterenol/kg, n=5, P<0.05). Sialidase activity in cardiomyocyte-derived H9c2 cells was also increased by treatment with isoproterenol (10 microM) for 60 min. The effect of isoproterenol on sialidase activity was amplified by the addition of 3-isobutyl-1-methylxanthine (IBMX). Sialidase activity in H9c2 cells was elevated by treatment with dibutyryl cAMP plus IBMX without isoproterenol. The content of N-acetylneuraminic acid in cells decreased by 22% after treatment with isoproterenol plus IBMX. These results suggest that sialidase activity in rat cardiomyocytes is regulated by beta-adrenergic stimulators via a cAMP-dependent process. The increased activity of sialidase may account for the reduction of sialic acid content of cells.
Department of Clinical Pharmacology and Therapeutics, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan. itomasa@smail.u-shizuoka-ken.ac.jp
Megumi
M
Saito
Katsuhiro
K
Sakiyama
Tomoko
T
Shiota
Masaki
M
Ito
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004789:Enzyme Activation; D007545:Isoproterenol / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D009206:Myocardium / Q000201:enzymology*; D032383:Myocytes, Cardiac / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology*; D019158:N-Acetylneuraminic Acid / Q000032:analysis; D009439:Neuraminidase / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D000318:Adrenergic beta-Agonists; D010726:Phosphodiesterase Inhibitors; D009439:Neuraminidase; D019158:N-Acetylneuraminic Acid; D007545:Isoproterenol; D015056:1-Methyl-3-isobutylxanthine