Milrinone effects in the isolated immature rabbit heart

M. D. Parrish, Timothy S Brannon, A. Payne, N. Ayres, David E Fixler

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2 Scopus citations


Milrinone, a new positive inotropic agent, was evaluated and compared to isoproterenol in an immature isolated isovolumic rabbit heart model. Three age groups were studied: newborns (0-6 days), juveniles (4-6 weeks old) and adults (5-7 months old). Heart rate did not change significantly with milrinone or isoproterenol in adults or juveniles, but increased in newborns from 144 ± 1 to 162 ± (SEM) 6 beats/min at peak milrinone effect. Milrinone had a greater effect on the contractility (maximum positive dP/dt) of the mature hearts, with newborns increasing to 134 ± 6% of baseline, juveniles to 154 ± 8% and adults to 216 ± 15%. Results were similar for isoproterenol, although the positive inotropic effect occurred over a wider dosage range for this drug. No additive effects of the two drugs were noted. We conclude, that although milrinone is a positive inotropic drug in all age groups studied, the response of the newborn heart is quantitatively much weaker than that of the adult.

Original languageEnglish (US)
Pages (from-to)328-337
Number of pages10
JournalDevelopmental Pharmacology and Therapeutics
Issue number6
StatePublished - 1988

ASJC Scopus subject areas

  • General Pharmacology, Toxicology and Pharmaceutics
  • Pharmacology (medical)


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