Key result
Increasing perfusate tonicity from 240 to 280 mOsmol/L increased cardiac output from 33.7 to 43.5 ml/min (p<=0.003), but further increases to 360 mOsmol/L decreased it to 36.5 ml/min.
Why the study?
Does changing perfusate osmolality using mannitol affect contractility in an isolated working rat left ventricle?
Does changing perfusate osmolality using mannitol affect contractility in an isolated working rat left ventricle?
Absolute Event Rate: 43.5% vs 33.7%
p-value: p=<=0.003
Changing perfusate osmolality using mannitol has a biphasic inotropic effect on isolated rat hearts, being positive at low osmolalities and negative above 320 mOsm.litre-1.
Optimal tonicity may enhance ex vivo contractility; leaves open translation to clinical cardioplegia or mannitol use.
OBJECTIVE: The aim was to evaluate the effect of hypertonic perfusate on isolated left ventricular mechanical and energetic characteristics. METHODS: An isolated working rat heart model was perfused with a hyponatraemic Krebs-Heinseleit bicarbonate buffer (240 mOsmol.litre-1). To this buffer was added increasing amounts of mannitol to achieve 280, 320, and 360 mOsmol.litre-1 perfusates. RESULTS: Left ventricular peak pressure, maximum time derivative of left ventricular pressure (dP/dtmax), and end systolic pressure were all increased to a maximum value at 280 or 320 mOsmol.litre-1 perfusate tonicity. A similar response was evident with cardiac output, which changed from 33.7(SEM 0.6) to 43.5(0.8) ml.min-1 following changing the perfusate tonicity from 240 to 280 mOsmol.litre-1 (p less than or equal to 0.003). However, increasing perfusate tonicity further decreased cardiac output to 36.5(1.3) ml.min-1 at 360 mOsmol.litre-1. Maximal left ventricular elastance remained unchanged during perfusion with increasing perfusate tonicities. CONCLUSIONS: Changing perfusate osmolality using mannitol has a positive inotropic effect at low osmolalities and a negative inotropic effect at perfusate osmolality greater than 320 mOsm.litre-1.
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Ben‐Haim et al. (1992) studied Isolated working rat left ventricle. Hypertonic perfusate (mannitol) vs. Hyponatraemic Krebs-Heinseleit bicarbonate buffer (240 mOsmol.litre-1) was evaluated on Cardiac output (p=<=0.003). Increasing perfusate tonicity from 240 to 280 mOsmol/L increased cardiac output from 33.7 to 43.5 ml/min (p<=0.003), but further increases to 360 mOsmol/L decreased it to 36.5 ml/min.
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