Key Points
- To assess the effects of the calcium sensitizer EMD 57033 on left ventricular mechanical performance and oxygen consumption across different heart rates, calcium concentrations, and loading conditions.
- Perfused 10 isolated rabbit hearts with red blood cells and administered EMD 57033 (5.0 to 5.8 µmol/L) across heart rates of 100 and 150 bpm and extracellular calcium levels of 1.0 and 2.5 mmol/L.
- Measured left ventricular pressures, relaxation kinetics, and myocardial oxygen consumption under isovolumic conditions and compared them to ejecting beats (n=7).
- EMD 57033 increased left ventricular developed pressure and maximum dP/dt while reducing time to peak pressure, but it also increased end-diastolic pressure and prolonged time to 50% relaxation.
- Increases in developed pressure were significantly greater in ejecting beats than isovolumic beats (25.5 ± 10.2 vs 14.7 ± 7.5 mm Hg at 100 bpm, P < .01).
- Increases in myocardial oxygen consumption were significantly higher for ejecting than isovolumic beats (0.027 ± 0.013 vs 0.020 ± 0.009 mL O2/beat per 100 g at 100 bpm, P < .01).
Structured PICO
PPopulation10 isolated, red blood cell-perfused rabbit hearts
IInterventionEMD 57033 (5.0 to 5.8 mumol/L)
OOutcomeLeft ventricular (LV) pressure and O2 consumption (VO2)surrogate
In isolated rabbit hearts, the calcium sensitizer EMD 57033 enhances contractility and prolongs relaxation, with positive inotropic effects being more prominent during ejecting beats.