title: Time dependent partial loss of the effects of isoproterenol on function and energy metabolism of isolated rat hearts.
abstract: In isolated perfused rat hearts (medium: Krebs-Ringer solution containing about 15% bovine red cells) the following parameters were estimated: heart rate (F), left intraventricular peak pressure (P), dP/dt, oxygen consumption (VO2); myocardial tissue content of glycogen, ATP, ADP, AMP, cAMP, phosphocreatin (PC) and inorganic phosphate (Pi). Isoproterenol (ISO) was administered to the non circulating system in the concentration range of 5 x 10(-10) to 5 x 10(-5) M for 4 min and 1 hour respectively by infusion into the perfusate close to the aortic canula. After administration period of 4 min dependent on the concentration of ISO, P, dP/dt, VO2 and the content of cAMP are increased. The ratios of PC/Pi and ATP/ADP as well as glycogen content are reduced. For an administration period of 1 hour at a level of 5 x 10(-9) M the effects of isoproterenol are maintained. At ISO concentration higher than 5 x 10(-9) M the effects on mechanical parameters and VO2 fall to the level of those values which are produced at 5 x 10(-9) M ISO. In contrast, high energy phosphates and glycogen content remain reduced while that of cAMP is elevated.
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004734:Energy Metabolism / Q000187:drug effects; D005260:Female; D006003:Glycogen / Q000378:metabolism; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D010477:Perfusion; D010710:Phosphates / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D051381:Rats; D013997:Time Factors
chemical_list: D000227:Adenine Nucleotides; D010710:Phosphates; D010725:Phosphocreatine; D006003:Glycogen; D007545:Isoproterenol