Evaluation of the isolated paced rat heart.
Ventricular performance and coronary flow in Langendorff perfused rat hearts were measured over a wide range of perfusion pressures and heart rates. A change in aortic pressure from 60 to 120 mmHg induced a linear increase in coronary flow, ventricular systolic pressure, and contractility. Ventricular pacing from 300 to 600 beats/min under a constant afterload had no effect on coronary flow. Systolic pressure remained stable up to 400-450 beats/min and then decreased 14% at 600 beats/min compared to the nonpaced controls. When contraction rate exceeded 450 beats/min diastolic pressure progressively increased as the heart rate was elevated. Contractility decreased rapidly between 450 and 600 beats/min under all perfusion pressures. These data indicate that this heart model is physiologically stable with heart rates less than 450 beats/min and may be useful in studying tachycardia-induced work overload.
D000818:Animals; D001794:Blood Pressure; D003326:Coronary Circulation; D004558:Electric Stimulation; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction; D010477:Perfusion; D051381:Rats; D016276:Ventricular Function