Abstract
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.
Footnotes
- Received February 4, 1970.
- Accepted July 14, 1970.
- © 1970 by The Williams & Wilkins Co.
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