title: Changes in cholinergic and adrenergic responses of organ-cultured chick smooth muscle.
abstract: Chick expansor secundariorum muscles were organ-cultured soon after hatching. Various contraction agonists or other agents were added to the nutrient medium to examine their effects on muscle chemosensitivity. The presence of noradrenaline, acetylcholine or barium chloride in the nutrient medium progressively reduced the maximum acetylcholine contraction, while the maximum noradrenaline contraction remained unaltered as compared to the BaCl2 or KCl contraction. The desensitizing effect of acetylcholine was abolished by adding atropine to the nutrient medium; the effect of noradrenaline was abolished by adding phentolamine or verapamil. Although 40 days are required after hatching for the acetylcholine response of this muscle to disappear in situ, the present findings suggest that already upon hatching, the acetylcholine response is susceptible to disappearance. Furthermore, the mechanism which abolishes the acetylcholine response of this smooth muscle may be closely related to muscle contraction.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002645:Chickens; D003470:Culture Media; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D009924:Organ Culture Techniques; D010275:Parasympathetic Nervous System / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D003470:Culture Media; D000109:Acetylcholine; D009638:Norepinephrine