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Cardiac myocyte growth response to IGF1 and increased systolic load in lambs (542.2)
Author(s) -
Wilburn Adrienne,
Giraud George,
Louey Samantha,
Jonker Sonnet
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.542.2
Subject(s) - myocyte , medicine , muscle hypertrophy , endocrinology , cardiac myocyte , fetus , cardiology , cardiac cycle , andrology , biology , pregnancy , genetics
The plasticity of the fetal heart allows a proliferative response to growth signals such as increased systolic arterial load (Load) and insulin‐like growth factor 1 (IGF1). The neonatal responses to these stimuli are unknown. OBJECTIVE To determine the in vivo growth response of neonatal cardiomyocytes to IGF1 and to Load compared to controls. METHODS Lambs were instrumented 7 days after birth with inflatable descending thoracic aortic occluders and vascular catheters. On 11‐18 days of age, lambs were given IGF1 (149 μg/kg/day, i.v.), vehicle (i.v.; control), or the occluder was inflated (final day: +35mmHg mean arterial pressure). Hearts were then enzymatically dissociated and myocyte size, maturation (nucleation), and cell cycle activity (an index of proliferation) were measured. RESULTS Hearts were heavier in Load (9.1±0.9 g/kg) and IGF1 (7.2±0.8 g/kg) groups compared to controls (6.6±0.4 g/kg). Cell cycle activity was not different between groups. In IGF1 lambs, mono and quadrinucleated right ventricular myocytes were significantly wider than controls (by 10% and 17%, respectively). In Load lambs, left ventricular mononucleated myocytes were significantly longer (by 14%), and there were 5% fewer binucleated myocytes compared to controls. CONCLUSIONS In the second week after birth, neonatal lamb cardiomyocytes respond to IGF1 and Load with cellular hypertrophy rather than proliferation. Grant Funding Source : Supported by R01HD071068.