Adenosine stimulation of AMP deaminase activity in adult-rat cardiac myocytes

B. Hu, R. A. Altschuld, C. M. Hohl*

*Corresponding author for this work

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Using an in situ assay for analyzing AMP deaminase activity in isolated adult rat ventricular myocytes, we have shown that IMP production is stimulated approximately twofold in cardiac cells incubated with 10 μM adenosine. This effect of adenosine was not blocked by the adenosine A1- receptor antagonist 8-cyclophenyl-1,3-dipropylxanthine (0.01-1 μM) except at a concentration (100 μM) that may inhibit adenosine transport. Similarly, in situ AMP deaminase activity was not enhanced by treatment with the specific adenosine A1-receptor agonists N6-phenylisopropyl adenosine or cyclopentyladenosine, nor was it sensitive to prior treatment of cells with pertussis toxin. The nucleoside transport blockers S-4-nitrobenzyl-6- thioinosine, dipyridamole, and papaverine inhibited adenosine-induced increases in IMP production by 75-85%, suggesting an intracellular site of action. Modulation of enzyme activity via the transmethylation pathway could not be implicated since incubation of cardiac cells under conditions known to elevate intracellular S-adenosyl-L-homocysteine had no demonstrable effect on AMP deaminase. Furthermore, a direct allosteric effect of adenosine on the partially purified rat cardiac enzyme was not observed. The results indicate that intracellular adenosine modulates rat cardiac AMP deaminase by an unknown mechanism.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume264
Issue number1 33-1
StatePublished - Jan 1 1993

Keywords

  • adenosine receptor
  • adenosine transport
  • adenylate deaminase
  • heart cells
  • inosine monophosphate

ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Physiology

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