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Myocardial region (right or left ventricle) and aetiology of heart failure can influence the inotropic effect of ouabain in failing human myocardium
Author(s) -
Roberto Padrini,
Marco Panfili,
Gianna Magnolfi,
Donatella Piovan,
D Casarotto,
Mariano Ferrari
Publication year - 1999
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1046/j.1365-2125.1999.00064.x
Subject(s) - inotrope , contractility , ventricle , medicine , ouabain , cardiology , heart failure , ejection fraction , chemistry , organic chemistry , sodium
Aims To investigate whether the inotropic effect of ouabain in failing human myocardium varies according to the heart chamber tested (right or left ventricle) or the aetiology of the heart disease, i.e. ischaemic or idiopathic.Methods The inotropic effect of ouabain was measured, as the percentage change in baseline tension, in myocardial strips isolated from right (RV; n=21) and left ventricles (LV; n=21) of hearts explanted from patients with idiopathic (IDC; n=11) and ischaemic cardiomyopathy (CAD; n=10). Concentration‐effect curves obtained with ouabain (0.05–1.6 μmol l −1 ) were analysed using the E max sigmoidal model, and the following parameters were calculated: E max , EC 50 , n and EC 10 (threshold concentration). The influence of ventricular chamber and heart failure aetiology on these parameters was evaluated by means of a two‐way anova.Results Age and baseline haemodynamic parameters did not differ between IDC and CAD patients. Baseline strip contractility was highly variable (range: 0.48–10.0 mN), but neither ventricular chamber nor aetiology could explain such variability. A two‐way anova showed that EC 10 was greater in CAD than in IDC preparations (0.097±0.013 μmol l −1 vs 0.059±0.009 μmol l −1 ; 95% C.I. for difference 0.043, 0.071) and E max was lower in RV than in LV (121±21%vs 250±38%; 95% C.I. −221, −36), while EC 50 and n were not significantly different between groups.Conclusions The inotropic effect of ouabain in human myocardium may vary according to aetiology of heart failure and the ventricle being tested. Although our results do not support the hypothesis of increased sensitivity to cardiac glycosides in CAD patients, they may explain the diminished effect observed in patients with RV failure.