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Azar N, Nasser M, Sabban ME, et al. Cardiac growth patterns in response to chronic hypoxia in a neonatal rat model mimicking cyanotic heart disease. Exp Clin Cardiol. 2003;8(4):189-94
Azar, N., Nasser, M., Sabban, M. E., Bitar, H., Obeid, M., Dbaibo, G. S., & Bitar, F. F. (2003). Cardiac growth patterns in response to chronic hypoxia in a neonatal rat model mimicking cyanotic heart disease. Experimental and clinical cardiology, 8(4), 189-94.
Azar, Nabil, et al. "Cardiac growth patterns in response to chronic hypoxia in a neonatal rat model mimicking cyanotic heart disease." Experimental and clinical cardiology vol. 8,4 (2003): 189-94.
Azar N, Nasser M, Sabban ME, Bitar H, Obeid M, Dbaibo GS, Bitar FF. Cardiac growth patterns in response to chronic hypoxia in a neonatal rat model mimicking cyanotic heart disease. Exp Clin Cardiol. 2003;8(4):189-94. PMID: 19649219; PMCID: PMC2719159.
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Exp Clin Cardiol. 2003;8(4):189-94.

Cardiac growth patterns in response to chronic hypoxia in a neonatal rat model mimicking cyanotic heart disease.

Experimental and clinical cardiology

Nabil Azar, Michel Nasser, Marwan El Sabban, Hala Bitar, Mounir Obeid, Ghassan S Dbaibo, Fadi F Bitar

Affiliations

  1. Departments of Pediatrics.

PMID: 19649219 PMCID: PMC2719159

Abstract

OBJECTIVE: Myocardial growth during fetal life is accomplished by the proliferation of myocytes. Shortly after birth, normal myocytes largely lose their capability to replicate. The present study aims to assess the effect of persistent postnatal hypoxia on myocardial growth patterns in an animal model mimicking cyanotic heart disease.

METHODS: Sprague-Dawley rats were placed in a normobaric hypoxic environment at birth and oxygen levels were maintained at 10% (group H). Controls (group C) remained in room air. The animals were sacrificed and the hearts were harvested at one, four and eight weeks.

RESULTS: Significant polycythemia developed in the hypoxic rats. There was a significant increase in indexed right ventricle (RV) and left ventricle (LV) masses compared with controls. Myocardial DNA concentrations were significantly increased in both ventricles of the hypoxic rats. For the RV, the increase in DNA content for group H was 135%, 132% and 112% that of group C values at one, four and eight weeks, respectively. RV and LV myocardial protein:DNA ratios were lower in the one-week- and four-week-old hypoxic rats, and significantly higher in the hypoxic eight-week-old rats. Polyploidy, hydroxyproline concentrations and dry:wet weight ratios were not significantly different in the LV and RV between both group H and group C animals.

CONCLUSION: Cardiac mass increases in response to chronic hypoxia were greater in the RV than the LV. This increase was mainly due to myocardial proliferation in the first four weeks of life. Although the three groups of hypoxic rats had significant elevations in DNA concentration compared with controls, there was a shift from proliferation to hypertrophy after week 4 of life. The age of the myocyte appears to be the most important factor in triggering proliferation in this hypoxic animal model.

Keywords: Cyanosis; Hypoxia; Myocardial growth; Rat

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