Increased aortic pressure produced small and inconsistent changes in the inotropic state of the left ventricle in isolated cat hearts and intact dogs, with peak isovolumic pressure differences ranging from -0.3 to +0.5 kPa.
Does increased aortic pressure alter the inotropic state of the left ventricle in cat and dog models?
Increased aortic pressure does not consistently alter the inotropic state of the left ventricle in isolated cat hearts or intact denervated dogs.
Effect estimate: difference in peak isovolumic pressure ranged from -0.3 to +0.5 kPa
The effect of increased aortic pressure on the inotropic state of the left ventricle was studied in isolated cat hearts, perfused with bovine red cells in Tyrode solution, ejecting into a hydraulic model with the same input impedance as that of the cat aorta.2. Inotropic state was assessed at a controlled left ventricular end-diastolic pressure by interpolating single isovolumic beats by means of an occluder in the aortic cannula.3. When such isovolumic beats during periods of raised aortic pressure were compared with those during control periods, the difference in peak isovolumic pressure ranged from -0.3 to +0.5 kPa indicating differences in inotropic state which were small and inconsistent in direction.4. The maximum rate of rise of left ventricular pressure (dP/dt(max).) of ejecting beats was little affected by a rise of aortic pressure and the direction of changes was inconsistent.5. The effect of increased aortic pressure was studied in intact dogs after cardiac denervation; left ventricular end-diastolic pressure was uncontrolled and therefore rose to a higher steady level.6. No consistent change of dP/dt(max). was found during the period of increased aortic pressure.7. All flow and pressure variables remained steady during the period of increased aortic pressure after the higher level of left ventricular end-diastolic pressure had been established.8. These results demonstrate that neither the positive inotropic effect nor the negative inotropic effect of increased load dominates in these preparations. This may be the result of a balance between the two effects, or they may be of unimportant magnitude under physiological conditions.
Elzinga et al. (Thu,) reported a other. Increased aortic pressure vs. Control periods (normal aortic pressure) was evaluated on Inotropic state of the left ventricle (difference in peak isovolumic pressure and dP/dt(max)) (difference in peak isovolumic pressure ranged from -0.3 to +0.5 kPa). Increased aortic pressure produced small and inconsistent changes in the inotropic state of the left ventricle in isolated cat hearts and intact dogs, with peak isovolumic pressure differences ranging from -0.3 to +0.5 kPa.