title: Contribution of nitrergic nerve in canine gingival reactive hyperemia.
abstract: Reactive hyperemia reflects a compensatory vasodilation response of the local vasculature in ischemic tissue. The purpose of this study is to clarify the mechanism of regulation of this response in gingival circulation by using pharmacological analysis of reactive hyperemia and histochemical analysis of gingival tissue. Application of pressure to the gingiva was used to create temporary ischemia, and gingival blood flow was measured after pressure release. Reactive hyperemia increased in proportion to the duration of pressure. Systemic hemodynamics remained unaffected by the stimulus; therefore, the gingival reactive hyperemia reflected a local adjustment in circulation. Gingival reactive hyperemia was significantly suppressed by nitric oxide (NO) synthase inhibitors, especially the neural NO synthase-selective antagonist 7-nitroindazole, but not by anticholinergic drugs, β-blockers, or antihistaminergic drugs. Moreover, immunohistochemical staining for neural NO synthase and histochemical staining for NADPH diaphorase activity were both positive in the gingival perivascular region. These histochemical and pharmacological analyses show that reactive hyperemia following pressure release is mediated by NO-induced vasodilation. Furthermore, histochemical analysis strongly suggests that NO originates from nitrergic nerves. Therefore, NO may play an important role in the neural regulation of local circulation in gingival tissue ischemia.
authors.affiliation: Department of Oral Science, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Shimada
authors.affiliation: Department of Nursing, Junior College, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Todoki
authors.affiliation: Department of Oral Science, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Omori
authors.affiliation: Department of Infection Control, Division of Microbiology, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Toshizo
authors.initials: T
authors.lastname: Toyama
authors.affiliation: Department of Tissue-Engineering, Institute for Frontier Oral Science, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Matsuo
authors.affiliation: Department of Oral Science, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Satoko
authors.initials: S
authors.lastname: Wada-Takahashi
authors.affiliation: Department of Oral Science, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Shun-Suke
authors.initials: SS
authors.lastname: Takahashi
authors.affiliation: Yokosuka-Shonan Disaster Health Emergency Research Center & ESR Laboratories, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-Cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Masaichi-Chang-Il
authors.initials: MC
authors.lastname: Lee
keywords: gingiva; nitrergic nerve; nitric oxide; reactive hyperemia