Inhibitory modulation of the reflex tracheal constriction induced by afferent vagal stimulation.
Afferent cervical vagal electrical stimulation caused a reflex tracheal constriction. Atropine changed the tracheal constriction into a tracheal dilatation that was almost inhibited by propranolol. In the hypertonic trachea with 5-hydroxytryptamine, a reflex dilatation following a constriction was observed by afferent vagal stimulation. The reflex dilatation was inhibited about 50% by propranolol and was abolished by hexamethonium. These results suggest that the adrenergic and nonadrenergic inhibitory innervations may mediate the reflex tracheal dilatation, especially in a hypertonic tracheal condition.
Misawa
M
M
Department of Applied Pharmacology, School of Pharmacy, Hoshi University, Tokyo, Japan.
Takahashi
Y
Y
Kamei
J
J
Hosokawa
T
T
Yanaura
S
S
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs; D004558:Electric Stimulation; D006339:Heart Rate / Q000187:drug effects; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009475:Neurons, Afferent / Q000502:physiology*; D011433:Propranolol / Q000494:pharmacology; D012018:Reflex / Q000187:drug effects; D012701:Serotonin / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects; D014630:Vagus Nerve / Q000502:physiology*
D006584:Hexamethonium Compounds; D012701:Serotonin; D001285:Atropine; D011433:Propranolol