title: Metabolic correlates of adenosine formation in stimulated guinea pig heart.
abstract: Adenosine release into epicardial fluid and coronary effluent of isolated isovolumic guinea pig hearts was examined at baseline and after stimulation with norepinephrine (30 nM) during 31P-nuclear magnetic resonance spectroscopy to monitor myocardial metabolism. At baseline flow (9.6 +/- 0.3 ml.min-1.g-1), epicardial and venous adenosine concentrations were 154 +/- 40 and 17 +/- 5 nM, respectively. The phosphorylation potential (log[ATP]/[ADP][Pi]) and the phosphocreatine-inorganic phosphate ratio ([PCr]/[Pi]) were 5.26 +/- 0.04 and 8.5 +/- 0.7, respectively. Norepinephrine increased left ventricular pressure, heart rate, and myocardial O2 consumption rate by approximately 21, 70, and 45%, respectively, and increased epicardial and venous adenosine to 496 +/- 74 and 461 +/- 94 nM, respectively. Log-[ATP]/[ADP][Pi] and [PCr]/[Pi] declined to 4.57 +/- 0.06 and 1.9 +/- 0.3, respectively. Epicardial [AMP] increased from 54 +/- 13 to 123 +/- 24 nM. AMP was not detectable in the venous effluent. Coronary resistance correlated with epicardial and venous [adenosine] (r = 0.86 and 0.90). Epicardial and venous [adenosine] correlated with log[ATP]/[ADP][Pi], [PCr]/[Pi], and cytosolic [AMP]. Hence, interstitial adenosine is linked to cytosolic metabolism and may regulate coronary vascular resistance. Venous adenosine underestimates epicardial adenosine at baseline but more closely approximates epicardial adenosine during norepinephrine infusion.
authors.affiliation: Department of Physiology, University of Virginia, Health Sciences Center, Charlottesville 22908.
authors.forename: J P
authors.initials: JP
authors.lastname: Headrick
authors.forename: G P
authors.initials: GP
authors.lastname: Matherne
authors.forename: S S
authors.initials: SS
authors.lastname: Berr
authors.forename: D C
authors.initials: DC
authors.lastname: Han
authors.forename: R M
authors.initials: RM
authors.lastname: Berne
mesh_terms: D000241:Adenosine / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology*; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D010725:Phosphocreatine / Q000378:metabolism; D010759:Phosphorus Isotopes; D010766:Phosphorylation / Q000187:drug effects
chemical_list: D010759:Phosphorus Isotopes; D010725:Phosphocreatine; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000241:Adenosine; D010100:Oxygen; D009638:Norepinephrine