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.
Saito
Megumi
M
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
Sakiyama
Katsuhiro
K
Shiota
Tomoko
T
Ito
Masaki
M
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