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January 1973

Cholinesterases and Contractility of Cat Irides: Effect of Echothiophate Iodide

Author Affiliations

New York
From the Department of Ophthalmology, New York Medical College (Drs. Harris and Shimmyo), and the Department of Pharmacology, Mount Sinai Hospital, 5th Ave and 100th St, New York (Dr. Mittag).

Arch Ophthalmol. 1973;89(1):49-51. doi:10.1001/archopht.1973.01000040051012

The effects on surface cholinesterases and contractility of intact cat irides treated with echothiophate iodide in vitro have been studied. Echothiophate, in contrast to diisopropylfluoro phosphate (DFP), more selectively inhibits true cholinesterases (ChE) than pseudo-ChE. Significant enzymatic inhibition is seen even with doses of echothiophate as low as 5 × 10-8 M, whereas DFP has little effect on these enzymes below 10-6 M concentration. The effects of echothiophate iodide on the acetyl-β-methylcholine dose-response curve and surface ChEs were completely reversed by in vitro treatment with pralidoxime chloride at 10-3 M.

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