title: Protective effects of (6R)-5,6,7,8-tetrahydro-l-biopterin on local ischemia/reperfusion-induced suppression of reactive hyperemia in rat gingiva.
abstract: We herein investigated the regulatory mechanism in the circulation responsible for rat gingival reactive hyperemia (RH) associated with ischemia/reperfusion (I/R). RH was analyzed using a laser Doppler flowmeter. RH and I/R were elicited by gingival compression and release with a laser Doppler probe. RH increased in a time-dependent manner when the duration of compression was between 30 s and 20 min. This increase was significantly suppressed by N (ω)-nitro-l-arginine-methyl-ester (l-NAME), 7-nitroindazole (7-NI), and 2,4-diamino-6-hydroxypyrimidine (DAHP). However, RH was markedly inhibited following 60 min of compression. This inhibition was significantly decreased by treatments with superoxide dismutase (SOD), (6R)-5,6,7,8-tetrahydro-l-biopterin (BH4), and sepiapterin. The luminescent intensity of superoxide anion (O2 (•-))-induced 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo-[1,2-a] pyrazine-3-one (MCLA) was markedly decreased by SOD and BH4, but only slightly by sepiapterin. BH4 significantly decreased O2 (•-) scavenging activity in a time-dependent manner. These results suggested that nitric oxide (NO) secreted by the nitrergic nerve played a role in regulating local circulation in rat gingiva. This NO-related regulation of local circulation was temporarily inhibited in the gingiva by the I/R treatment. The decrease observed in the production of NO, which was caused by suppression of NO synthase (NOS) activity subsequent to depletion of the NOS co-factor BH4 by O2 (•-), played a partial role in this inhibition.
authors.affiliation: Department of Oral Science, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Yusaku
authors.initials: Y
authors.lastname: Tanaka
authors.affiliation: Division of Microbiology, Department of Infection Control, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Toshizo
authors.initials: T
authors.lastname: Toyama
authors.affiliation: Department of Oral Science, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Satoko
authors.initials: S
authors.lastname: Wada-Takahashi
authors.affiliation: Division of Microbiology, Department of Infection Control, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Haruka
authors.initials: H
authors.lastname: Sasaki
authors.affiliation: Department of Oral Science, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Miyamoto
authors.affiliation: Department of Oral Science, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Yojiro
authors.initials: Y
authors.lastname: Maehata
authors.affiliation: Department of Oral Science, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Yoshino
authors.affiliation: Department of Oral Science, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Yoshida
authors.affiliation: Department of Oral Science, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Shun-Suke
authors.initials: SS
authors.lastname: Takahashi
authors.affiliation: Division of Microbiology, Department of Infection Control, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Yokosuka-Shonan Disaster Health Emergency Research Center & ESR Laboratories, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Masaichi-Chang-Il
authors.initials: MC
authors.lastname: Lee
authors.affiliation: Department of Health Science, School of Nursing, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Todoki
authors.affiliation: Division of Microbiology, Department of Infection Control, Graduate School of Dentistry, Kanagawa Dental University, 82 Inaoka-cho, Yokosuka, Kanagawa 238-8580, Japan.
authors.forename: Nobushiro
authors.initials: N
authors.lastname: Hamada
keywords: BH4; gingiva; nitric oxide synthases; reactive hyperemia; reperfusion