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Departments of Anesthesiology, Physiology and Pharmacology, Hypertension & Vascular Disease Center, and the Sticht Center on Aging, Wake Forest University School of Medicine, Winston-Salem, North Carolina.
Address correspondence to Leanne Groban, MD, Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1009. E-mail: lgroban{at}wfubmc.edu
We tested the hypothesis that long-term growth hormone (GH) replacement in aged rats would preserve diastolic function and attenuate left ventricular remodeling associated with normal aging. Male Brown Norway x F344 rats were randomized to receive twice daily injections of porcine GH (200 µg/injection, subcutaneous) or saline from 24 to 30 months of age. Adult rats (6- to 9-months old) received saline injections throughout the study. Thirty-month-old, saline-treated rats exhibited low levels of insulin-like growth factor 1 (IGF-1), impaired diastolic left ventricular filling (Doppler), increased cardiac angiotensin II (Ang II), reduced plasma Ang II, and increased cardiac collagen. GH administration in old rats restored IGF-1 and diastolic indices to values comparable to those of adults. These effects were associated with reduced cardiac Ang II and attenuations in cardiac collagen. Age-related decreases in GH and IGF-1 may contribute to the decline in diastolic function of aging, in part through alterations in reninangiotensin system-mediated ventricular remodeling.
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