title: Adenosine production and release by adult rat cardiocytes.
abstract: We have examined adenosine (ADO) production and transport in a preparation of isolated adult cardiocytes which attach to and form a monolayer on culture dishes. This preparation contains 85% viable cells which are greater than 50% rod shaped and maintain an ATP/ADP ratio of nine. Incubation under control conditions for 15 mins results in a net release of 240 +/- 47 pmol ADO/mg protein (final adenosine concentration in the medium = 47 +/- 9 nM). Both 0.1 mM dinitrophenol (DNP) and 10 mM iodoacetate (IAA) cause a significant increase in ADO (DNP = 1763 +/- 147 and IAA = 612 +/- 90 pmol/mg). Both 20 microM nitrobenzylthioinosine (NBMPR), an inhibitor of the purine nucleoside carrier, and 0.1 mM alpha,beta-methylene adenosine diphosphate (AOPCP), an inhibitor of 5'-nucleotidase activity, attenuate DNP-stimulated ADO release (NBMPR by 62% and ADOCP by 76%). The results are consistent with the hypothesis that under the conditions of our experiments, adenosine is formed by a 5'-nucleotidase in association with transport across the cell membrane, perhaps by an enzyme-carrier complex. In addition, we have examined the effect of 0.1 mM dipyridamole on the extracellular appearance of adenosine in this preparation and found that it causes a significant increase in the amount of adenosine released. These results are consistent with the hypothesis that dipyridamole inhibits adenosine's uptake more than its release in cardiac myocytes.
mesh_terms: D015720:5'-Nucleotidase; D000241:Adenosine / Q000096:biosynthesis* / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active; D004140:Dinitrophenols / Q000494:pharmacology; D004176:Dipyridamole / Q000494:pharmacology; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D009708:Nucleotidases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013868:Thioinosine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D004140:Dinitrophenols; D007461:Iodoacetates; C523965:alpha,beta-methyleneadenosine 5'-diphosphate; D013868:Thioinosine; D000244:Adenosine Diphosphate; D004176:Dipyridamole; D000255:Adenosine Triphosphate; D009708:Nucleotidases; D015720:5'-Nucleotidase; C001789:4-nitrobenzylthioinosine; D000241:Adenosine; D019807:Iodoacetic Acid