title: High k(+)-induced relaxation by nitric oxide in human gastric fundus.
abstract: This study was designed to elucidate high K(+)-induced relaxation in the human gastric fundus. Circular smooth muscle from the human gastric fundus greater curvature showed stretch-dependent high K(+) (50 mM)-induced contractions. However, longitudinal smooth muscle produced stretch-dependent high K(+)-induced relaxation. We investigated several relaxation mechanisms to understand the reason for the discrepancy. Protein kinase inhibitors such as KT 5823 (1 µM) and KT 5720 (1 µM) which block protein kinases (PKG and PKA) had no effect on high K(+)-induced relaxation. K(+) channel blockers except 4-aminopyridine (4-AP), a voltage-dependent K(+) channel (K(V)) blocker, did not affect high K(+)-induced relaxation. However, N(G)-nitro-L-arginine and 1H-(1,2,4)oxadiazolo (4,3-A)quinoxalin-1-one, an inhibitors of soluble guanylate cyclase (sGC) and 4-AP inhibited relaxation and reversed relaxation to contraction. High K(+)-induced relaxation of the human gastric fundus was observed only in the longitudinal muscles from the greater curvature. These data suggest that the longitudinal muscle of the human gastric fundus greater curvature produced high K(+)-induced relaxation that was activated by the nitric oxide/sGC pathway through a K(V) channel-dependent mechanism.
authors.affiliation: Department of Surgery, Chungbuk National University College of Medicine, Cheongju 361-763, Korea.
authors.forename: Dae Hoon
authors.initials: DH
authors.lastname: Kim
authors.forename: Young Chul
authors.initials: YC
authors.lastname: Kim
authors.forename: Woong
authors.initials: W
authors.lastname: Choi
authors.forename: Hyo-Young
authors.initials: HY
authors.lastname: Yun
authors.forename: Rohyun
authors.initials: R
authors.lastname: Sung
authors.forename: Hun Sik
authors.initials: HS
authors.lastname: Kim
authors.forename: Heon
authors.initials: H
authors.lastname: Kim
authors.forename: Ra Young
authors.initials: RY
authors.lastname: Yoo
authors.forename: Seon-Mee
authors.initials: SM
authors.lastname: Park
authors.forename: Sei Jin
authors.initials: SJ
authors.lastname: Yun
authors.forename: Young-Jin
authors.initials: YJ
authors.lastname: Song
authors.forename: Wen-Xie
authors.initials: WX
authors.lastname: Xu
authors.forename: Sang Jin
authors.initials: SJ
authors.lastname: Lee
keywords: Fundus; High K+; Human stomach; Longitudinal smooth muscle; Nitric oxide; Relaxation