Studies of the neuromuscular blocking effects of BW 403C65 in frog and cat muscle.
BW 403C65, an isoquinolinium bisquaternary compound, was investigated for its neuromuscular blocking properties. In vitro in from preparations, low concentrations induced an increase in miniature endplate potentials (m.e.p.p.) frequency without altering their amplitude. With increasing concentrations m.e.p.p. frequency returned to control value and amplitude started to decrease concomitantly with the decreased sensitivity of the endplate to iontophoretically applied acetylcholine and depression of the twitch tension. Acetylcholine released at the neuromuscular junction was also decreased. In vivo in the cat preparation  the intra-arterial injection of low doses of the drug produced an increase in the strength of the muscle twitch, and the development of contracture, as well as the appearance of post-drug repetition at the ventral roots. Greater doses produced a progressive decline in post-tetanic potentiation with prolonged return to control.
D000109:Acetylcholine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D001001:Anura; D002415:Cats; D055598:Chemical Phenomena; D002621:Chemistry; D004149:Dioxoles / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009045:Motor Endplate / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009466:Neuromuscular Blocking Agents / Q000494:pharmacology*; D011806:Quinolinium Compounds / Q000494:pharmacology*
D004149:Dioxoles; D009466:Neuromuscular Blocking Agents; D011806:Quinolinium Compounds; C011384:BW 403C65; D000109:Acetylcholine