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This Article Full Text Full Text (PDF) All Versions of this Article: 292/6/H3119    most recent 00588.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Spier, S. A. Articles by Muller-Delp, J. M. Search for Related Content PubMed PubMed Citation Articles by Spier, S. A. Articles by Muller-Delp, J. M.

Exercise training enhances flow-induced vasodilation in skeletal muscle resistance arteries of aged rats: role of PGI₂ and nitric oxide

¹Department of Health and Kinesiology, University of Texas at Tyler, Tyler, Texas; ²Division of Exercise Science, Department of Physiology and Pharmacology, Center for Interdisciplinary Research in Cardiovascular Sciences, West Virginia University School of Medicine, Morgantown, West Virginia; and ³Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, Texas

Submitted 5 June 2006 ; accepted in final form 13 February 2007

Flow-induced vasodilation is attenuated with old age in rat skeletal muscle arterioles. The purpose of this study was to determine whether diminished cyclooxygenase (COX) signaling contributes to the age-induced attenuation of flow-induced vasodilation in gastrocnemius muscle arterioles and to determine whether, and through which mechanism(s), exercise training restores this deficit in old rats. Fischer 344 rats (3 and 22 mo old) were assigned to a sedentary or exercise-trained group. First-order arterioles were isolated from the gastrocnemius muscles, cannulated, and pressurized to 70 cmH₂O. Diameter changes were determined in response to graded increases in intraluminal flow in the presence and absence of nitric oxide synthase (NOS) inhibition [10^–5 M N^G-nitro-L-arginine methyl ester (L-NAME)], COX inhibition (10^–5 M indomethacin), or combination NOS (10^–5 ML-NAME) plus COX (10^–5 M indomethacin) inhibition. Aging reduced flow-induced vasodilation in gastrocnemius muscle arterioles. Exercise training restored responsiveness to flow in arterioles of aged rats and enhanced flow-induced vasodilation in arterioles from young rats. L-NAME inhibition of flow-induced vasodilation was greater in arterioles from old rats compared with those from young rats and was increased after exercise training in arterioles from both young and old rats. Although the indomethacin-sensitive portion of flow-induced dilation was not altered by age or training, both COX-1 mRNA expression and PGI₂ production increased with training in arterioles from old rats. These data demonstrate that exercise training restores flow-induced vasodilation in gastrocnemius muscle arterioles from old rats and enhances flow-induced vasodilation in gastrocnemius muscle arterioles from young rats. In arterioles from both old and young rats, the exercise training-induced enhancement of flow-induced dilation occurs primarily through a NOS mechanism.

aging; endothelium; prostacyclin; cyclooxygenase

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