%0 Journal Article %A ALEXANDER G. KARCZMAR %A K. C. KIM %A K. KOKETSU %T ENDPLATE EFFECTS AND ANTAGONISM TO d-TUBOCURARINE AND DECAMETHONIUM OF TETRAETHYLAMMONIUM AND OF METHOXYAMBENONIUM (WIN 8078) %D 1961 %J Journal of Pharmacology and Experimental Therapeutics %P 199-205 %V 134 %N 2 %X Tetraethylammonium (TEA) and methoxyambenonium (WIN 8078), compounds capable of antagonizing neuromyal blockade produced either by d-tubocurarine (dTc) or decamethonium (C10), were studiedon the frog nervesartorius muscle preparations. The endplate potential (e.p.p.) obtained in presence of either dTc or C10 was augmented and somewhat prolonged by TEA with resulting repetitive firing. WIN 8078 augmented but did not prolong e.p.p. and did not cause repetitive firing. Neither compound produced depolarization. C10 depolarization was temporary; blockade of neuromyal transmission occurred at termination of C10 depolarization and at the time of endplate desensitization to acetylcholine (ACh). TEA desensitized the endplate to ACh and further reduced endplate sensitivity after C10 WIN 8078 sensitized the endplate and restored its sensitivity following ACh desensitization by C10. These findings are discussed from the viewpoint of the mechanism of action of WIN 8078 and TEA, as well as of C10 blockade. It is suggested that WIN 8078 and TEA antagonism of C10 is in part due to non-depolarizing character of neuromyal blockade by the latter and in part dependsupon unusualendplateactivities of WIN 8078 and TEA. © 1961, by The Williams & Wilkins Company %U https://jpet.aspetjournals.org/content/jpet/134/2/199.full.pdf