Abstract
ABSTRACT: Effects of s.c. administration of dexamathasone (1–25 μg/rat pup/d) during the first 5 d postpartum on survival rates, body weight, heart weight, heart-to-body weight ratios, and heart dimensions were determined. Dexamethasone decreased survival, body weight, and heart weight, but increased heart-to-body weight ratios and myocardial percentage of dry weight (0.44 to 0.52–1.06 and 20 to 23%, respectively; p < 0.05) by 7 d postpartum. By 21 d postpartum, differences in absolute body weight and heart weight between control and experimental animals were reduced; however, myocardial percentage of dry weight and heart-to-body weight ratios were indistinguishable. Microscopic analysis of 7-d-old hearts disclosed that interventricular septum, left ventricular free wall thicknesses, and left ventricle chamber diameter were reduced (0.93 to 0.76–0.85 mm, 1.19–1.34 to 0.92–1.07 mm, and 1.35–1.40 to 0.89–1.23 mm, respectively; p < 0.05), whereas right ventricular free wall thickness was unaffected and right ventricle chamber diameter was increased (0.29–0.31 to 0.42–0.46 mm) by dexamethasone. Thus, dexamethasone reduced survival and retarded growth of neonatal rats. Retardation of heart growth was less severe, producing a transient relative cardiomegaly characterized by 1) increased myocardial percentage of dry weight, 2) increased left ventricular free wall-to-chamber ratio, and 3) retention of absolute right ventricular free wall thickness. This relative cardiomegaly appeared to be resolved by 21 d postpartum, as reflected in myocardial percentage of dry weight and heart-to-body weight ratios. These data suggest that this system might be a useful model for elucidating cellular and molecular mechanisms through which ventricular hypertrophy might arise in infants receiving dexamethasone therapy for bronchopulmonary dysplasia.
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Sicard, R., Werner, J. Dexamethasone Induces a Transient Relative Cardiomegaly in Neonatal Rats. Pediatr Res 31, 359–363 (1992). https://doi.org/10.1203/00006450-199204000-00011
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DOI: https://doi.org/10.1203/00006450-199204000-00011
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