CORRELATION OF MANOMETRIC AND HISTOCHEMICAL TECHNIQUES IN THE STUDY OF CHOLINESTERASE ACTIVITY

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Abstract
1. A relationship is defined for the manometric equivalent of the activity of cholinesterase which will precipitate a minimally visible deposit of copper sulfide, when Koelle's technique for demonstration of cholinesterase is applied to plasma and erythrocyte enzyme preparations. 2. Were the equations for the histochemical reactions exactly defined, with particular reference to the structural formula of copper thiocholine, the equivalence could be calculated from the stoichiometric equations. In the absence of exact knowledge of the equations, equivalence is estimated by techniques which adapt a filter paper matrix as substitute for tissue. 3. Calculations are limited to order of magnitude at minimal staining, so that surface deposits of copper sulfide can be studied without reference to their depth. 4. The motor end-plate of rat intercostal muscle, with surface area of about 500 sq. micra is shown to have a cholinesterase activity of an order of magnitude capable of hydrolyzing 2.5 x 10–6 microliters of carbon dioxide in 30 minutes. 5. The cholinesterase activity of rat erythrocyte is estimated as being below the threshold of activity per unit area necessary to result in a visible precipitate of copper sulfide with the histochemical method employed.