title: Cholinergic sensitivity: normal variability as a function of stimulus background.
abstract: The sensitivity of the normally innervated iris sphincter to its neuro-transmitter, acetylchloline, and to relatd agents varies inversely with the preexisting physiological stimulus background, that is, the environmental light intnsity. This normal variability suggests the existence of a negative feedback mechahnism whereby sensitivity of the effector cell is modutlated by a product of neuronal activity.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000221:Adaptation, Ocular; D000818:Animals; D002415:Cats; D003215:Conditioning, Eyelid; D003623:Dark Adaptation; D005246:Feedback; D007498:Iris / Q000187:drug effects*; D008688:Methacholine Compounds / Q000494:pharmacology; D010277:Parasympathomimetics / Q000494:pharmacology*; D010862:Pilocarpine / Q000494:pharmacology; D009435:Synaptic Transmission
chemical_list: D008688:Methacholine Compounds; D010277:Parasympathomimetics; D010862:Pilocarpine; D000109:Acetylcholine