Differential cardiac effects of growth hormone and insulin-like growth factor-1 in the rat. A combined in vivo and in vitro evaluation.
BACKGROUND: Despite their increasing clinical use and recent evidence that growth hormone (GH) and insulin-like growth factor-1 (IGF-1) target the heart, there has been no systematic investigation of the effects of GH and IGF-1 on the cardiovascular system. METHODS AND RESULTS: Sixty normal but growing adult female rats were randomized to receive 4 weeks of treatment with GH (3.5 mg.kg-1.d-1), IGF-1 (3 mg.kg-1.d-1), a combination of the two, or placebo. Transthoracic echocardiograms were performed at baseline and at 2 weeks and 4 weeks of treatment. After the final echocardiography, rats underwent either closed-chest left ventricular (LV) catheterization or Langendorff perfusion studies. Myocyte diameter and interstitial tissue fraction were assessed by morphometric histology. Echocardiographic and ex vivo data demonstrated a LV hypertrophic response in all three groups of treated animals that was most marked in the GH group, which alone exhibited a concentric growth pattern (relative wall thickness, 0.52 versus 0.42 to 0.44 in the other groups; P < .001). At 4 weeks, cardiac index was significantly higher and total systemic vascular resistance was lower in all groups of treated animals than in control animals (both P < .001), whereas arterial blood pressure did not differ significantly. All indexes of in vivo and in vitro cardiac function were higher in GH- and IGF-1-treated rats than in control animals, whereas combination therapy yielded a blunted effect. Myocyte diameter was increased in all three treated groups without an increase in interstitial tissue. CONCLUSIONS: Exogenous administration of GH and IGF-1 in the normal adult rat induces a cardiac hypertrophic response without development of significant fibrosis. Cardiac performance is increased both in vivo and in the isolated heart.
Duke Scholars
Altmetric Attention Stats
Dimensions Citation Stats
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Ventricular Function, Left
- Rats, Sprague-Dawley
- Rats
- Myocardial Contraction
- Insulin-Like Growth Factor I
- In Vitro Techniques
- Hypertrophy, Left Ventricular
- Humans
- Hemodynamics
- Heart
Citation
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Ventricular Function, Left
- Rats, Sprague-Dawley
- Rats
- Myocardial Contraction
- Insulin-Like Growth Factor I
- In Vitro Techniques
- Hypertrophy, Left Ventricular
- Humans
- Hemodynamics
- Heart