Comparison of positive inotropic effects of milrinone, dobutamine and ouabain

S. V. Rendig, Ezra A Amsterdam

Research output: Contribution to journalArticlepeer-review


This study compared the positive inotropic actions of milrinone in isolated rabbit myocardium with that of the conventional positive inotropic drug, dobutamine, and a cardiac glycoside, ouabain. Maximal increase in developed tension (g/mm2) was significantly (p < 0.05) greater with ouabain (from 2.0 to 4.4; 132 ± 11%) than with dobutamine (from 3.9 to 6.0; 77.8 ± 22.4%) or milrinone (from 2.4 to 3.6; 54.0 ± 12.0%). Maximal augmentation of the rate of tension development (g/s/mm2), however, was similar with ouabain (from 14.3 to 39.7; 187 ± 20%) and dobutamine (from 25.9 to 64.4; 174 ± 35%), and both were significantly (p < 0.05) greater than with milrinone (from 18.2 to 30; 73.1 ± 14.7%). In combination with dobutamine, however, the dose-response curve of milrinone was shifted to the left, and its ED10 was significantly (p < 0.001) reduced by 100-fold to 1.6 x 10-7M. Thus, milrinone is significantly less potent than dobutamine or ouabain in vitro and is without contractile effect at clinically relevant concentrations. However, data from the combined application of a catecholamine and milrinone in isolated myocardium suggest that milrinone may induce a direct positive inotropic effect at clinical concentrations in the presence of augmented sympathetic neurohumoral stimulation.

Original languageEnglish (US)
Pages (from-to)99-105
Number of pages7
Issue number2
StatePublished - 1994


  • Catecholamine
  • Digitalis glycoside
  • Phosphodiesterase inhibitor
  • Rabbit papillary muscle

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine


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