title: Influence of heart rate on metabolic and hemodynamic parameters in the Syrian hamster cardiomyopathy.
abstract: The effect of varying heart rate in 155- to 170-day-old isolated, perfused cardiomyopathic Syrian hamster hearts was evaluated by 31P nuclear magnetic resonance spectroscopy. At a low paced heart rate of 170 bpm, cardiomyopathic hearts did not differ from normal hearts except for a lower developed left ventricular pressure. As pacing rate was increased progressively to 270/min, cardiomyopathic hearts showed prolongation of contraction, which led to a pronounced rise in diastolic pressure as the interstimulus interval shortened. This was accompanied by a marked decrease in energy-rich phosphorus compounds. By contrast, increasing heart rate in normal hearts did not change left ventricular pressure and caused only a mild reduction in energy-rich phosphorus compounds. Intracellular pH of cardiomyopathic animals paced at 270 bpm was significantly lower than in normal animals. Thus, indices reflecting mitochondrial function of 155- to 170-day-old cardiomyopathic hamsters appear adequate at low heart rate. Increasing the heart rate unmasks latent mitochondrial dysfunction.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure; D003326:Coronary Circulation; D006224:Cricetinae; D004734:Energy Metabolism; D006333:Heart Failure / Q000378:metabolism* / Q000503:physiopathology; D006339:Heart Rate; D009682:Magnetic Resonance Spectroscopy; D008647:Mesocricetus; D010101:Oxygen Consumption; D010758:Phosphorus / Q000378:metabolism
chemical_list: D010758:Phosphorus; D000255:Adenosine Triphosphate