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Developmental changes in mRNA encoding cardiac Na+/H+ exchanger (NHE-1) in rabbit
F Chen1, J M Jarmakani, C Van Dop
1Division of Pediatric Cardiology, University of California, Los Angeles 90095-1752, USA.
Biochemical and Biophysical Research Communications
|July 26, 1995
Summary
Newborn rabbit hearts show faster recovery from acidosis due to higher Na+/H+ exchanger-1 (NHE-1) activity. NHE-1 mRNA levels are significantly higher in fetal and newborn hearts compared to adult hearts, explaining this difference.
Area of Science:
- Cardiovascular Physiology
- Molecular Biology
- Developmental Biology
Background:
- Neonatal cardiac contractility recovers faster during acidosis than adult hearts.
- This difference is linked to the activity of the Na+/H+ exchanger (NHE).
Purpose of the Study:
- To investigate the developmental changes in cardiac Na+/H+ exchanger-1 (NHE-1) mRNA expression in rabbits.
- To correlate NHE-1 mRNA levels with functional differences in cardiac contractility during acidosis.
Main Methods:
- Quantification of NHE-1 mRNA in fetal, newborn, and adult rabbit ventricles.
- Utilized reverse transcription-polymerase chain reaction (RT-PCR) and RNase protection assay.
- GAPD mRNA was used as an internal standard for normalization.
Main Results:
- NHE-1 mRNA levels were similar in fetal and newborn rabbit hearts.
- NHE-1 mRNA expression was significantly higher (1.7x and 1.6x) in fetal and newborn hearts compared to adult hearts.
- These findings correlate with previously observed developmental changes in Na+/H+ exchanger activity.
Conclusions:
- Cardiac NHE-1 mRNA expression is developmentally regulated in rabbits.
- Higher NHE-1 mRNA levels in younger rabbits likely contribute to their enhanced ability to handle acidosis.
- This study highlights the molecular basis for improved neonatal cardiac function under stress.
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