Summary
Measurements of transmethylation rate (approximately 750 pmol min−1 g−1) and total adenosine production rate (approximately 800 pmol min−1 g−1) in isolated, perfused guinea pig hearts have demonstrated that hydrolysis of S-adenosylhomocysteine is the primary source of intracellular adenosine during normoxia (95% O2). Furthermore, adenosine kinase appears not to be substrate-saturated. When the rate of adenosine synthesis is increased 50-fold by hypoxic perfusion (30% O2) there is little alteration in the rate of cellular transmethylation (approximately 1200 pmol min−1 g−1). Experiments using an adenosine analogue, tricyclic nucleoside (TCN), to selectively mark the intracellular 5′-AMP pool by conversion to TCN-monophosphate, demonstrated that hypoxia enhanced both adenosine and TCN release rates. These findings suggest that during hypoxia the primary source of adenosine is 5′-AMP and that the increased rate of 5′-AMP hydrolysis is due not only to an increased substrate concentration but also to deinhibition of 5′-nucleotidase.
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Llyod, H.G.E., Schrader, J. (1987). The Importance of the Transmethylation Pathway for Adenosine Metabolism in the Heart. In: Gerlach, E., Becker, B.F. (eds) Topics and Perspectives in Adenosine Research. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-45619-0_16
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DOI: https://doi.org/10.1007/978-3-642-45619-0_16
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