The interaction of amiloride with acetylcholinesterase and butyrylcholinesterase.

The diuretic drug amiloride was found to be a powerful inhibitor of the reaction of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with their specific choline ester substrates. The inhibition constant is in the micromolar range. On the other hand, when added to a mixture of cholinesterase (AChE and BChE) and neutral substrates, amiloride, in some cases, enhanced the reaction rate. The rate of the reaction of butyrylcholinesterase with p-nitrophenyl butyrate was increased up to 12 fold by amiloride.