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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Short Term Growth Hormone Adminstration on Aortic Residual Strain

Authors
item Caperna, Thomas
item Vossoughi, J. - UNIV OF DC ENGINEERING
item Hilbert, S. - US FDA/OFFICE SCI & TECHN
item Haudenschild, Cc - AMERCIAN RED CROSS
item Zuckerman, MD - US FDA/DEVICE EVAL OFFICE

Submitted to: International Journal of Cardiovascular Medicine and Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 18, 1999
Publication Date: N/A

Interpretive Summary: Administration of porcine growth hormone is associated with altered nutrient partitioning such that protein deposition is enhanced at the expense of energetic efficiency. We have previously shown that collagen deposition and composition are altered by treatment of pigs with growth hormone. In addition, growth hormone treatment is associated with an increase in the mass of visceral tissue including the heart and other cardiovascular tissues. Since the mechanical properties of tissues are associated with connective tissue proteins, this study has focused on the alteration in mechanical stresses in aortas of growth hormone-treated pigs. Eight pigs were administered porcine growth hormone daily for two weeks and eight additional pigs served as buffer-treated controls. Growth hormone treatment was associated with a 36% increase in growth rate. At the end of the treatment period, aortas were measured and removed for the determination of residual strain, which is a measure of the internal mechanical stress of the tissue structure upon removal of all external loads. Residual strain was highest in the most anterior region of the thoracic aorta and decreased caudally along the length of the aorta. Administration of GH was associated with a 35% overall increase in the residual strain of the aorta, while distribution of residual strain along the aorta was similar for control and pGH-treated pigs. These data suggest that growth hormone may have significant influence on mechanical properties of aortic tissues and may impact hemodynamic function.

Technical Abstract: Eight crossbred pigs (41.5 ñ 0.6 kg) were administered porcine pituitary growth hormone (pGH, 100 ug/kg) daily for two weeks. Eight additional pigs (41.4 ñ 0.6 kg) served as controls, and were administered a similar amount of diluent solution daily. Treatment with pGH resulted in a 36% increase in growth rate. At the end of the treatment period, aortas were measured and removed for the determination of residual strain, which is a measure o the internal mechanical stress of the tissue structure when all external loads are removed. Each aorta was sliced into 30, three-mm rings. Each ring was kept flat in a saline-filled plastic dish and photographed. The ring was then cut radially which caused it to spring open into a horse shoe-shape; this new configuration was also photographed. From the photographs, the intimal residual strain was calculated. Residual strain was highest in the most anterior region of the thoracic aorta and decreased dcaudally along the length of the aorta. Administration of GH was associated with a 35% overall increase in the residual strain of the aorta, while distribution of residual strain along the aorta was similar for control and pGH-treated pigs. These data suggest that growth hormone may have significant influence on mechanical properties of aortic tissues and may impact hemodynamic function.

Last Modified: 12/28/2014
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