Effects of vanadate on responses of guinea-pig isolated trachea to spasmogens.
The effects of vanadate on the contractility of the guinea-pig isolated trachea was examined. Vanadate (0.1 mM) produced a sustained contraction that was abolished in Ca(2+)-free EGTA (0.1 mM)-containing physiological salt solution but was resistant to verapamil (1 microM). Vanadate (0.1 mM) depressed tracheal responses to CaCl2 (in Ca(2+)-free depolarizing solution), KCl, acetylcholine, histamine and 5-hydroxytryptamine. For vanadate (10 microM), the inhibition of spasmogenic responses only reached statistical significance for histamine and 5-hydroxytryptamine. Caffeine (1 mM)-induced spasm (trachea at 20 degrees C in the presence of indomethacin (2.8 microM)) was not affected by vanadate (10 microM-0.1 mM). Vanadate (0.1 mM) slightly depressed the responses to KCl (50 mM), acetylcholine (1 mM), histamine (1 mM) or 5-hydroxytryptamine (0.1 mM) observed in Ca(2+)-free EGTA (0.1 mM)-containing physiological salt solution. Vanadate (0.5 mM) depressed Ca2+ (20 microM)-induced contraction of trachea which had been chemically skinned of its plasmalemmal membranes. The mechanism of the inhibitory effect of vanadate on tracheal responses to a variety of spasmogens remains obscure, but, under in-vitro conditions, vanadate clearly does not induce hyper-reactivity of airway smooth muscle to spasmogens.
Cortijo
J
J
Departamento de Farmacologia, Facultat de Medicina i Odontologia, Universitat de Valéncia, Spain.
Santamaría
P
P
Antón
M
M
Villagrasa
V
V
Morcillo
E
E
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology / Q000502:physiology; D002462:Cell Membrane / Q000502:physiology; D005260:Female; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D010277:Parasympathomimetics / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects*; D014638:Vanadates / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology
D010277:Parasympathomimetics; D012701:Serotonin; D002110:Caffeine; D014638:Vanadates; D011189:Potassium Chloride; D006632:Histamine; D014700:Verapamil; D000109:Acetylcholine; D002118:Calcium