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This Article Full Text Full Text (PDF) All Versions of this Article: 293/3/H1498    most recent 01190.2006v1 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 ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Sakai, N. Articles by Ohhashi, T. Search for Related Content PubMed PubMed Citation Articles by Sakai, N. Articles by Ohhashi, T.

High oxygen tension constricts epineurial arterioles of the rat sciatic nerve via reactive oxygen species

Departments of ¹Physiology and ²Orthopaedic Surgery, Shinshu University School of Medicine, Matsumoto, and ³Department of Electronics and Control Engineering, Nagano National College of Technology, Nagano, Japan

Submitted 30 October 2006 ; accepted in final form 17 May 2007

Microcirculation of the sheath of the rat sciatic nerve fiber was investigated by using an intravital microscope, and changes in the diameter of the epineurial arterioles in response to highly oxygenated Krebs-bicarbonate solution were evaluated. Superfusion of low-oxygen (0%) Krebs-bicarbonate solution (LKS) onto rat sciatic nerves did not affect changes in the diameter of the arterioles. Nifedipine, a Ca²⁺-channel blocker, caused a dose-dependent dilation of the epineurial arterioles in LKS. In contrast, superfusion of high-oxygen (21%) Krebs-bicarbonate solution (HKS) onto rat sciatic nerves significantly constricted the epineurial arterioles in a time-dependent manner. The HKS-induced constriction of the epineurial arterioles was significantly reduced by treatment with 120 U/ml superoxide dismutase (SOD) alone or 5,000 U/ml catalase alone. In the presence of 120 U/ml SOD plus 5,000 U/ml catalase, 10^–4 M tempol, 10^–6 M diphenyleneiodium, 2 x 10^–4 M apocynin, or 10^–6 M allopurinol, the HKS-induced constriction of the epineurial arterioles completely disappeared. These results suggest that superfusion of highly oxygenated solution onto rat sciatic nerves constricts the epineurial arterioles through reactive oxygen species (ROS), including superoxide and hydrogen peroxide, and that production of superoxide involves a NADPH oxidase- or xanthine oxidase-dependent pathway. In conclusion, ROS play significant roles in the regulation of microcirculation of rat sciatic nerves in vivo.

peripheral nerves; microcirculation; superoxide; hydrogen peroxide