Formation and Deamination of Adenosine by Cardiac Muscle Enzymes

• Published in: Molecular pharmacology Vol. 2; no. 1; pp. 67 - 76
• Main Authors: Baer, H P, Drummond, G I, Duncan, E L
• Format: Journal Article
• Language: English
• Published: United States American Society for Pharmacology and Experimental Therapeutics 01.01.1966
• Subjects: Adenine Nucleotides - biosynthesis; Animals; In Vitro Techniques; Myocardium - enzymology; Nucleosides - biosynthesis; Rats
• ISSN: 0026-895X; 1521-0111

The enzymic catabolism of adenylic acid has been studied in rat heart. AMP may be degraded by two routes, one involving dephosphorylation to adenosine followed by deamination to inosine, the other involving deamination to inosinic acid followed by dephosphorylation to inosine. The data are consistent with the role of adenosine as a regulator of coronary flow. The 5'-nucleotidase and adenosine deaminase have been isolated and partially purified from rat heart acetone powder. The deaminase has also been partially purified from red blood cells. ATP is a potent competitive inhibitor of 5'-nucleotidase and could function as a regulator for the production of adenosine. The substrate specificity of adenosine deaminase has been examined. Several adenosine analogs function as competitive inhibitors of both the heart and red cell enzyme. The most potent inhibitors tested were N 6 -methyladenosine and 6-methoxypurine ribonucleoside. The coronary dilator, Persantin, does not inhibit cardiac adenosine deaminase at concentrations as high as 4 x 10 -4 M.