Effects of pH-regutatory Na/H exchange (NHE) inhibition in Ischémie newborn rabbit myocardium

Hong Liu, Peter M Cala, S. E. Anderson

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Abstract

The hypothesis that inhibition of pH-regulatory NHE during ischemia decreases Na uptake and thereby Ca upiake via Na/Ca exchange to limit Na- and Ca-dependent ATP depletion was tested in newborn ischémie hearts. 31p. 23Na and 19F NMR were used to measure intracellular pH (pHj), Na(Naj), C'a(Caj) and ATP in isolated newborn (4-7 dayO lahbit hearts Langendorff-perfused with bicarbonate buffered Krebs-Henseleit solution; pH 7.4±0.5 after equilibration with 95%O2/5%CO2 at 37'C. Both control and experimental groups had 30 min baseline, 40 min ischemia and 40 min reperfusion. Hth>lisopropylamiloride(ErPA 10 uM) was added to inhibit NHE. Data are meaniSEM, p<0.05 Group{n) Baseline End Ischemia End Reperfusion pH, control (41 7.IQ±0.005 5.73+/U2 7.11+0.01 FIFA (4) 7.10±0.02 5.88±0.01 7.12±0.01 Ca. inM/L) control (4) :79±39 1I06±8t> 737±49 EIPA (4i 295±49 710±66 3I2±61 Nu; a>ntml(4} 12±0.9 114+16 5.H12 (intq/kgdry) EIPA (4) 19.4+2.8 24.1+1.7 17.2+1.8 ATP ' control (4) 100+0.9 20.7±7 I 34.7±8.3 (% of Control) EIPA(4) 100+1.7 32+5.0 53±4.4 The data show that EIPA decreases changes in Naj and Caj during ischemia. At the end ol reperfusion Caj is lower and ATP is higher in EIPA treated hearts than in control hearts during reperfusion. We conclude that the data support the hypothesis and suggest that Na/H exchange inhibition decreases changes in newborn myocardium associated with ischémie and repertusion injury. This could be of particular benefit for newborn lu-ari protection and preservation during open-heart surgery and heart transplantation.

Original languageEnglish (US)
JournalFASEB Journal
Volume10
Issue number3
StatePublished - 1996

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ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Cell Biology

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