RT Journal Article SR Electronic T1 SPECIFIC SUBSENSITIVITY OF THE RAT ATRIUM TO CHOLINERGIC DRUGS JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 496 OP 502 VO 175 IS 2 A1 SHARON E. PERRINE A1 JOSEPH J. McPHILLIPS YR 1970 UL http://jpet.aspetjournals.org/content/175/2/496.abstract AB The sensitivity of the atrium to drugs was studied subsequent to the subacute administration of the cholinesterase inhibitor O, O-diethyl S-2-(ethylthio) ethyl phosphorodithioate (Di-Syston) to rats. Initial rates of the atria were unaffected by treatment. However, the doses of carbachol and bethanechol which slowed the atrial rate 125 beats/min (ED125) increased approximately 3- fold as a result of the treatment. The atria were more sensitive to acetyicholine and methacholine, but there was no change in the sensitivity of the atrium to veratramine or epinephrine. The ability of atropine to antagonize carbachol was not altered by Di-Syston treatment since the pA2, values for atropine did not change. Single injections of Di-Syston caused potentiation of the effects of acetylcholine but did not alter the sensitivity of the atrium to carbachol. © 1970 by The Williams & Wilkins Co.