STUDIES ON THE MECHANISM OF ACTION OF DFP AND TEPP

¹ Pharmacology Branch, Chemical Corps Medical Laboratories, Army Chemical Center, Maryland

1. DFP and TEPP produce readily reversible (by time) decreases in (a) the tension developed by directly stimulated, denervated skeletal muscle; (b) the amplitude of the spike potential of nerve; (c) the tension developed by skeletal muscle stimulated by slow (30/minute) excitation of its motor nerve; and (d) spinal and respiratory reflexes.

2. Within the duration of our experiments (10 hours), DFP and TEPP produce irreversible decreases in (a) cholinesterase in the motor end-plate on skeletal muscle; (b) cholinesterase in the spinal cord; and (c) the ability of skeletal muscle to maintain a plateau of tension during excitation of its motor nerve at 50/second.

3. Animals which had died after administration of DFP had complete or nearly complete removal of cholinesterase activity from the motor end-plates of skeletal muscle and from the spinal cord; TEPP can produce death despite the presence of considerable quantities of cholinesterase in the spinal cord and in the respiratory and other striated muscles.

4. It is suggested that the reversible actions of DFP and TEPP may not result solely from cholinesterase inhibition.