Parameters of ventricular contractility in mice: influence of load and sensitivity to changes in inotropic state
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We examined the relative usefulness of parameters to determine left ventricular contractility in mice invasively. The optimal parameter must be sensitive to changes in inotropy and insensitive to changes in loading. Furthermore, it should be able to confirm or reject the hypothesis of altered myocardial contractility after a limited number of experiments. Left ventricular function was assessed in closed-chest mice using a microtip pressure-conductance catheter at baseline and after increases in preload, afterload, or contractility. The parameters are differentially influenced by loading conditions and inotropic state. Only those parameters that could differentiate between basal and increased contractility with a power of 0.85 in ten or less experiments were considered useful. Ejection fraction, preload-recruitable stroke work (PRSW), and dP/dtmax/Ved could demonstrate the smallest changes in contractility. Stroke work, maximal power and dP/dtmax were most influenced by preload. End-systolic elastance, ejection fraction, and stroke work were afterload-dependent. Dividing the magnitude of the effect of inotropic stimulation to that of load changes gives an index for the usefulness for each parameter. A high ratio indicates that the change in parameter reflects inotropic rather than load change. This ratio was highest for PRSW, which seems to be the best parameter for judging contractility differences in mice.
KeywordsMyocardial contraction Mice Ventricular function Heart function tests
- 4.Borow KM, Neumann A, Marcus RH, Sareli P, Lang RM (1992) Effects of simultaneous alterations in preload and afterload on measurements of left ventricular contractility in patients with dilated cardiomyopathy: comparisons of ejection phase, isovolumetric and end-systolic force–velocity indexes. J Am Coll Cardiol 20:787–795PubMedGoogle Scholar
- 7.Feneley MP, Skelton TN, Kisslo KB, Davis JW, Bashore TM, Rankin JS (1992) Comparison of preload recruitable stroke work, end-systolic pressure–volume and dP/dtmax-end-diastolic volume relations as indexes of left ventricular contractile performance in patients undergoing routine cardiac catheterization. J Am Coll Cardiol 19:1522–1530PubMedGoogle Scholar
- 9.Georgakopoulos D, Kass DA (2002) Assessment of Cardiovascular function in the mouse using pressure–volume relationships. Acta Cardiol Sin 18:101–112Google Scholar
- 20.Opie L (2004) Heart physiology. From cell to circulation. 4th edn. Lippincott Williams & WIlkins, PhiladelphiaGoogle Scholar