ISSN:
1432-1440
Keywords:
Amrinone
;
Ouabain
;
Positive inotropy
;
Cat papillary muscles
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Amrinone has been shown to produce haemodynamic benefits in digitalis-treated patients. Since amrinone is a positive inotropic agent on isolated heart muscle, these benefits may mean that amrinone increases the maximal ouabain-induced increase in force of contraction, without causing toxicity. We have therefore measured, in cat right ventricular papillary muscles, the inotropic effects of ouabain, amrinone alone and amrinone with a maximally effective, non-toxic ouabain concentration (2×10−7 M). Ouabain is much more potent than amrinone (EC50-values: ouabain, 8×10−8 M, amrinone, 1–2.8×10−3 M). The highest amrinone concentration used (6×10−3 M) produced a significantly lower increase in force of contraction than ouabain (2×10−7 M) in the same muscles. After ouabain (2×10−7 M) produced a stable effect, no further increase in force of contraction was observed with any amrinone concentration. Sustained arrhythmias were observed in five of six muscles at 3×10−3 M amrinone with ouabain (2×10−7 M), but in only one of these muscles with amrinone 3×10−3 M alone. Since the positive inotropic effects of amrinone are not additive with those from a maximally effective ouabain concentration, the haemodynamic benefits seen in patients are probably due to non-cardiac effects of amrinone such as vasodilatation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01742294
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