HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 100/5/1563    most recent 01035.2005v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal 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 DeLorey, D. S. Articles by Buckwalter, J. B. Search for Related Content PubMed PubMed Citation Articles by DeLorey, D. S. Articles by Buckwalter, J. B.

-Adrenergic receptor-mediated restraint of skeletal muscle blood flow during prolonged exercise

Departments of Anesthesiology and Physiology, Medical College of Wisconsin, and Veterans Affairs Medical Center, Milwaukee, Wisconsin

Submitted 24 August 2005 ; accepted in final form 10 January 2006

Sympathetic nervous system restraint of skeletal muscle blood flow during dynamic exercise has been well documented. However, whether sympathetic restraint of muscle blood flow persists and is constant throughout prolonged exercise has not been established. We hypothesized that both ₁- and ₂-adrenergic receptors would restrain skeletal muscle blood flow throughout prolonged constant-load exercise and that the restraint would increase as a function of exercise duration. Mongrel dogs were instrumented chronically with transit-time flow probes on the external iliac arteries and an indwelling catheter in a branch of the femoral artery. Flow-adjusted doses of selective ₁- (prazosin) and ₂-adrenergic receptor (rauwolscine) antagonists were infused after 5, 30, and 50 min of treadmill exercise at 3 and 6 miles/h. During mild-intensity exercise (3 miles/h), prazosin infusion resulted in a greater (P < 0.05) increase in vascular conductance (VC) after 5 [42% (SD 6)], compared with 30 [28% (SD 6)] and 50 [28% (SD 8)] min of running. In contrast, prazosin resulted in a similar increase in VC after 5 [29% (SD 10)], 30 [24% (SD 9)], and 50 [22% (SD 9)] min of moderate-intensity (6 miles/h) exercise. Rauwolscine infusion resulted in a greater (P < 0.05) increase in VC after 5 [39% (SD 14)] compared with 30 [26% (SD 9)] and 50 [22% (SD 4)] min of exercise at 3 miles/h. Rauwolscine infusion produced a similar increase in VC after 5 [19% (SD 3)], 30 [15% (SD 6)], and 50 [16% (SD 2)] min of exercise at 6 miles/h. These results suggest that the ability of ₁- and ₂-adrenergic receptors to produce vasoconstriction and restrain blood flow to active muscles may be influenced by both the intensity and duration of exercise.

vascular conductance; sympathetic nervous system; sympatholysis

This article has been cited by other articles:

				D. S. DeLorey, J. J. Hamann, Z. Valic, H. A. Kluess, P. S. Clifford, and J. B. Buckwalter {alpha}-Adrenergic receptor responsiveness is preserved during prolonged exercise Am J Physiol Heart Circ Physiol, January 1, 2007; 292(1): H392 - H398. [Abstract] [Full Text] [PDF]