The absence of the descending limb of the Frank-Starling curve of the depressed guinea pig whole ventricle.
To determine whether the descending limb of the Frank-Starling curve can be detected in the whole ventricle when contractile state is impaired, volume-active pressure relationships were investigated in deteriorated preparations of isolated guinea pig hearts. The pressure developed by the isovolumic left ventricle as well as the first derivative of the pressure were determined during progressive dilation of the left ventricle up to a resting pressure of 60 mmHg. Coronary flow was provided by a constant perfusion pressure of 75 mmHg. The descending limb of the Frank-Starling curve was not detected: when expressed as a function of resting pressure the coronary flow attained maximal values at a calculated resting pressure of 14.0 mmHg and decreased at larger ventricular volumes. These results support the view that there is no descending limb of the Frank-Starling curve when the whole ventricle is distended, even when the intrinsic contractile properties are impaired, and coronary flow is reduced by compression due to ventricular distension.
D000818:Animals; D001794:Blood Pressure; D002302:Cardiac Output; D003326:Coronary Circulation; D006168:Guinea Pigs; D006321:Heart / Q000502:physiology*; D008297:Male; D009200:Myocardial Contraction; D010477:Perfusion; D016276:Ventricular Function