The Annals of Thoracic Surgery, Vol 54, 124-129, Copyright © 1992 by The Society of Thoracic Surgeons
Myocardial protection of neonatal heart by cardioplegic solution with recombinant human superoxide dismutase
S Tatebe, M Nakazawa, H Miyamura, J Hayashi, S Eguchi and S Imai
Department of Pharmacology, Niigata University School of Medicine, Japan.
The effectiveness of high-potassium cardioplegic solution in the neonatal
heart remains controversial. Our previous study indicated that the
protection afforded by a cardioplegic solution was inadequate in the
neonatal heart. On the hypothesis that oxyradicals were responsible for the
ineffectiveness of cardioplegic solution in neonatal heart, the effects of
a cardioplegic solution (a modified St. Thomas' Hospital cardioplegic
solution) with recombinant human superoxide dismutase on the isolated
perfused neonatal guinea pig hearts (within 2 days after delivery, body
weight of 60 to 120 g) were studied in comparison with those on the adult
hearts (6 to 8 weeks after delivery, body weight of 300 to 500 g). After
arrest induced by modified St. Thomas' Hospital cardioplegic solution,
hearts were subjected to 120 min of ischemia at 20 degrees C, during which
time the cardioplegic solution was injected every 30 minutes. Then the
heart was reperfused for 60 minutes at 37 degrees C. Under this condition,
the left ventricular developed pressure recovered to 84.4% +/- 4.0% of the
preischemic value in the adult heart, whereas the recovery was only 68.1%
+/- 3.1% in the neonatal heart. Thiobarbituric acid-reactive substance
level, a parameter of lipid peroxidation by oxyradicals, significantly
increased during ischemic arrest both in the adult and neonatal heart.
However, the increase was much greater in the neonatal heart than in the
adult. Cardioplegia with recombinant human superoxide dismutase (300 and
1,000 U/mL) significantly inhibited this accumulation of thiobarbituric
acid- reactive substance in the neonatal heart; at 1,000 U/mL, the
myocardial function of the reperfused neonatal heart recovered to the level
of the adult heart.(ABSTRACT TRUNCATED AT 250 WORDS)