The pharmacology of the cholinoceptor in muscle preparations of Ascaris lumbricoides var. suum.
1. The preparation of a muscle strip of Ascaris lumbricoides for the study of the effect of drugs in vitro is described.2. Stimulant drugs which are classified as nicotine-like in mammalian pharmacology increased the isometric tension of this preparation. These drugs were, in descending order of potency: dimethylphenylpiperazinium, nicotine, acetylcholine, carbachol, decamethonium and pyridine-2-aldoxime methiodide.3. Muscarine-like drugs (oxotremorine, methacholine, pilocarpine) had no activity.4. Potassium and barium ions stimulated the tissue, while the anti-cholinesterases, dichlorvos and eserine, increased the resting tension of the preparation and potentiated the responses to acetylcholine.5. Adrenaline neither stimulated the tissue nor affected the responses to nicotine-like drugs.6. The relative potency of several blocking agents which antagonize the responses to nicotine-like drugs was assayed. These blocking agents were, in descending order of potency: mecamylamine, (+)-tubocurarine, hexamethonium, atropine and piperazine. Acetylcholine, dimethylphenylpiperazinium and pyridine-2-aldoxime methiodide apparently act on a common receptor, for each blocking agent had a similar molar inhibitory concentration against these stimulants.7. It is concluded that the cholinoceptor in muscle preparations of Ascaris lumbricoides is pharmacologically similar to that of the mammalian autonomic ganglion.
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001200:Ascaris / Q000187:drug effects*; D001285:Atropine / Q000494:pharmacology; D001464:Barium / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D003650:Decamethonium Compounds / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005730:Ganglionic Blockers / Q000494:pharmacology; D006584:Hexamethonium Compounds / Q000494:pharmacology; D066298:In Vitro Techniques; D008464:Mecamylamine / Q000494:pharmacology; D009132:Muscles / Q000187:drug effects*; D009538:Nicotine / Q000494:pharmacology*; D010276:Parasympatholytics / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011955:Receptors, Drug; D014403:Tubocurarine / Q000494:pharmacology
D002800:Cholinesterase Inhibitors; D003650:Decamethonium Compounds; D005730:Ganglionic Blockers; D006584:Hexamethonium Compounds; D010276:Parasympatholytics; D010879:Piperazines; D011955:Receptors, Drug; D001464:Barium; D008464:Mecamylamine; D009538:Nicotine; D001285:Atropine; D002217:Carbachol; D000109:Acetylcholine; D011188:Potassium; D014403:Tubocurarine; D004837:Epinephrine