Possible stimulation of Na+-K+-ATPase by NO produced from sodium nitrite by ultraviolet light in mouse gastric fundal strip.
1. In the present study, we investigated the roles of Na+-K+-ATPase and extracellular Na+ or Ca2+ ions in ultraviolet (UV) light-induced photorelaxation of methacholine-contracted mouse isolated gastric fundus in the presence of NaNO2 (50 microM). 2. Ouabain (1-500 microM), sodium vanadate (10 microM to 3 mM) and amiloride (1-100 microM) completely inhibited the photorelaxation in a concentration-dependent manner. 3. Metabolic inhibitors, sodium azide (10-100 microM), 2,4-dinitrophenol (100 microM to 1 mM) and sodium fluoride (100 microM to 1 mM) significantly reduced photorelaxation. 4. Substitution of sucrose, lithium or KCl with extracellular Na+ completely abolished the photorelaxant responses. 5. Replacement of all extracellular CaCl2 with BaCl2 also completely inhibited UV-induced relaxation. 6. Verapamil (1-10 microM) decreased UV-induced relaxation significantly. 7. These results suggest that nitric oxide produced from NaNO2 by UV-light in mouse gastric fundus probably stimulates Na+-K+-ATPase activity, and photorelaxation of gastric smooth muscle is dependent on extracellular Na+ and Ca2+ ions.
Yaktubay
N
N
Department of Pharmacology, Faculty of Medicine, Cukurova University, Adana, Turkey.
Ogülener
N
N
Onder
S
S
Baysal
F
F
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology; D005260:Female; D005748:Gastric Fundus / Q000502:physiology / Q000528:radiation effects*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D009126:Muscle Relaxation / Q000187:drug effects / Q000528:radiation effects; D009569:Nitric Oxide / Q000502:physiology*; D010042:Ouabain / Q000494:pharmacology; D012964:Sodium / Q000502:physiology; D012977:Sodium Nitrite / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology*; D014466:Ultraviolet Rays; D014638:Vanadates / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D009569:Nitric Oxide; D014638:Vanadates; D010042:Ouabain; D000584:Amiloride; D012964:Sodium; D014700:Verapamil; D000254:Sodium-Potassium-Exchanging ATPase; D012977:Sodium Nitrite; D002118:Calcium