title: Rebound contraction by nitric oxide in the longitudinal muscle of porcine gastric fundus.
abstract: The rebound contraction induced by electrical field stimulation (EFS) and nitric oxide (NO) donor, S-nitroso-L-cysteine (cysNO), were investigated in the longitudinal muscle of porcine gastric fundus (LM-PGF). Under the presence of atropine and guanethidine, cysNO and EFS produced sequential relaxation-contraction in LM-PGF. Tetrodotoxin abolished the EFS-induced response, while leaving the cysNO-induced one unaffected. A soluble guanylate cyclase inhibitor, 1H-[1,2,4]-oxadiazolo-[4,3-a]-quinoxalin-1-one, inhibited both cysNO and EFS-induced biphasic response. A cGMP analogue only relaxed LM-PGF. A phosphodiesterase V inhibitor, zaprinast, prolonged the cysNO and the EFS-induced relaxation and inhibited the rebound contraction. The rebound contraction was inhibited by verapamil, an L-type Ca2+ channel blocker. The cysNO and the EFS-induced biphasic response were inhibited by ryanodine plus cyclopiazonic acid or by ruthenium red, a ryanodine-receptor blocker. LM-PGF was relaxed on exposure to caffeine and then produced a verapamil-sensitive rebound contraction during the washout period. CysNO and EFS did not induce the rebound contraction in the presence of caffeine. These results suggest that the NO-induced rebound contraction involves both Ca2+-release from the ryanodine-sensitive store and Ca2+-influx through L-type channels. Although the NO-induced biphasic response is dependent on cGMP, rapid removal of cGMP seems necessary for the rebound contraction.
authors.affiliation: Department of Veterinary Physiology, College of Veterinary Medicine, Seoul National University, Suwon, Republic of Korea.
authors.forename: Junho
authors.initials: J
authors.lastname: La
authors.forename: Taewan
authors.initials: T
authors.lastname: Kim
authors.forename: Taesik
authors.initials: T
authors.lastname: Sung
authors.forename: Jeongwoo
authors.initials: J
authors.lastname: Kang
authors.forename: Hyunju
authors.initials: H
authors.lastname: Song
authors.forename: Hyunju
authors.initials: H
authors.lastname: Kim
authors.forename: Ilsuk
authors.initials: I
authors.lastname: Yang
mesh_terms: D000818:Animals; D005748:Gastric Fundus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D013552:Swine
chemical_list: D020030:Nitric Oxide Donors; D009569:Nitric Oxide