Abstract
Effects of ouabain (0.75, 1, 1.5, 2.5, or 5 × 10−6M) on mechanical function and sodium pump were studied in the isolated arterially perfused fetal and newborn rabbit heart. Measurements of myocardial 86Rb+ active uptake was used as a marker of the sodium pump activity. The inotropic effect of ouabain in the fetus was not significantly different from that in the newborn at all ouabain concentrations. 2.5 × 10−6M ouabain caused mechanical toxicity in the fetus but not in the newborn. In the fetal muscle, perfusion with low calcium (0.5 mM) solution reduced mechanical toxicity of ouabain. High extracellular calcium (30 mM) per se caused mechanical toxicity in the fetus, but not in the newborn. Ouabain infusion decreased tissue potassium content, and this decrease in the fetus was not significantly different from the newborn. The ouabain inhibition of Rb+ uptake was similar in the two age groups. These data indicate that mechanical toxicity in the fetus is observed at lower ouabain concentrations than in the newborn. This difference in mechanical toxicity may not be explained by the age-related difference in sodium pump activity. The greater calcium toxicity in the fetus may be the reason for the increased ouabain toxicity in this age group.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Jarmakani, J., Nakanishi, T., Shimizu, T. et al. EFFECT OF OUABAIN ON MYOCARDIAL MECHANICAL FUNCTION AND SODIUM PUMP IN THE PREMATURE NEWBORN RABBIT. Pediatr Res 18 (Suppl 4), 123 (1984). https://doi.org/10.1203/00006450-198404001-00183
Issue Date:
DOI: https://doi.org/10.1203/00006450-198404001-00183