Epinephrine and propranolol significantly shifted the peak isovolumic pressure-volume curve of the puppy left ventricle, altering maximum pressure to 160 mmHg and 110 mmHg vs 130 mmHg in control.
How do inotropic changes with epinephrine and propranolol affect the peak isovolumic pressure-volume relation in the left ventricle of puppies?
The peak isovolumic pressure-volume curve of the puppy left ventricle is convex upward and shifts sensitively with inotropic changes.
We studied peak isovolumic pressure-volume (PV) relation of the left ventricle in 3-mo-old mongrel puppies. A puppy heart was excised and cross circulated with an adult dog. Left ventricular pressure and volume were measured with a water-filled balloon. Peak isovolumic PV curve in control contractile state was convex upward, reaching a maximum pressure of 130 mmHg. Epinephrine (0.6 microgram/min intracoronary) shifted the curve leftward and up to a maximum pressure of 160 mmHg. Propranolol (0.8 mg intracoronary) shifted it rightward and down to a maximum pressure of 110 mmHg. These PV curves were reasonably fitted by an asymptotic equation: P = A (1 - exp-B (V - Vd)), where V was normalized volume for 100 g left ventricle and Vd (6 ml/100 g) was V at which peak pressure was zero. A and B are regression coefficients. A was 149, 169, and 120 mmHg, and B was 0.16, 0.19, and 0.06 ml, respectively, in control, enhanced, and depressed contractile states. These changes in A and B were statistically significant. We conclude that the puppy left ventricular peak isovolumic PV curve is convex upward and shifts sensitively with inotropic changes.
Suga et al. (Sat,) reported a other. Epinephrine and Propranolol vs. Control contractile state was evaluated on Peak isovolumic pressure-volume relation. Epinephrine and propranolol significantly shifted the peak isovolumic pressure-volume curve of the puppy left ventricle, altering maximum pressure to 160 mmHg and 110 mmHg vs 130 mmHg in control.