TY - JOUR T1 - EFFECTS OF 2-PAM AND TMB-4 ON NEUROMUSCULAR TRANSMISSION JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 311 LP - 319 VL - 149 IS - 3 AU - Joseph H. Fleisher AU - Thomas H. Moen AU - Niles H. Ellingson Y1 - 1965/09/01 UR - http://jpet.aspetjournals.org/content/149/3/311.abstract N2 - 2-PAM shows both excitatory and depressant actions on time responses of the isolated frog rectus abdominis and rat phrenic nerve-diaphragm preparations. The excitatory effect of 2-PAM on time response of time frog rectus abdominis muscle to acetylcholine appears to result from the anticholinesterase property of this oxime and not from a direct depolarizing action. 2-PAM depresses the response to the depolarizing agents decamethonium and carbamylcholine which are not susceptible to hydrolysis by cholinesterase and also to acetylcholine in the eserinized frog rectus preparation. TMB-4 showed no excitatory effects; instead its inhibitory actions on the response of time frog rectus to decamethonium, carbamylcholine and acetylcholine appeared stronger than those of 2-PAM. Evidence was presented to show that at high dosage levels quaternary oximes increase neuromuscular block of the rat diaphragm preparation following prolonged exposure to a nonhydrolyzable depolarizer like decamethonium or to acetylcholine protected from hydrolysis by an anticholinesterase against which the oximes are ineffective. The Williams & Wilkins Comapny ER -