Effects of aging and exercise training on endothelium-dependent vasodilation of skeletal muscle arterioles /
Aging reduces endothelium-dependent vasodilation in both humans and animals. In humans, exercise training reverses the aging-associated reduction in endothelium-dependent vasodilation. However, the mechanism(s) through which these alterations occur have not been established. The purpose of this s...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2003.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=764887771&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Aging reduces endothelium-dependent vasodilation in both humans and animals. In humans, exercise training reverses the aging-associated reduction in endothelium-dependent vasodilation. However, the mechanism(s) through which these alterations occur have not been established. The purpose of this study was to determine the mechanism(s) by which exercise training enhances endothelium-dependent vasodilation in arterioles from muscles of differing fiber composition in young and old rats. One hundred and eight Fischer 344 rats, ages 3- and 22-months old, were assigned to either a young sedentary (young SED, n = 25), young exercise-trained (young ET, n = 31), old sedentary (old SED, n = 28), or old exercise-trained (old ET, n = 24) group. Exercise-trained groups ran on a treadmill 60 min/d at 15 m/min (15⁰ incline), 5 d/wk for 10 - 12 wk. 1A arterioles were isolated from the soleus and superficial gastrocnemius muscles of each animal. Luminal diameter changes were determined in response to graded increases in intraluminal flow at constant intraluminal pressure and to acetylcholine (ACh, 10⁻⁹ - 10⁻⁴ M), an endothelium-dependent vasodilator. Responses to flow and ACh were then determined in the presence of nitric oxide synthase (NOS) inhibition (L-NAME, 10⁻⁵ M), cyclooxygenase (COX) inhibition (Indomethacin, 10⁻⁵ M), or combination NOS (L-NAME, 10⁻⁵ M) plus COX (Indomethacin, 10⁻⁵ M) inhibition. Aging reduced flow-induced vasodilation, and these age-associated reductions were eliminated by NOS inhibition in soleus muscle arterioles and COX inhibition in gastrocnemius muscle arterioles. ACh-mediated vasodilation was reduced only in soleus muscle arterioles of aged rats, and these reductions were abolished with NOS inhibition. Exercise training ameliorated the aging-induced reduction in endothelium-dependent vasodilation to flow and ACh in soleus muscle arterioles and to flow in gastrocnemius muscle arterioles. NOS blockade and the combined NOS plus COX blockade abolished the training-induced enhancement of flow-mediated vasodilation in arterioles from both muscles of aged rats and the training-induced enhancement of ACh-mediated vasodilation in arterioles from soleus muscle of aged rats. These data demonstrate that exercise training can restore old age-associated reductions in endothelium-dependent vasodilation, and that this restoration occurs through a nitric oxide mechanism in both the soleus and gastrocnemius muscles. |
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| Item Description: | Vita. "Major Subject: Kinesiology". |
| Physical Description: | x, 63 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 56-62). |