Echothiophate and cogeners decrease the voltage dependence of end-plate current decay in frog skeletal muscle.

Article Details

Citation

Copy to clipboard

Henderson EG, Post-Munson DJ, Reynolds LS, Epstein PM

Echothiophate and cogeners decrease the voltage dependence of end-plate current decay in frog skeletal muscle.

J Pharmacol Exp Ther. 1989 Dec;251(3):810-6.

PubMed ID

2481033 [ View in PubMed

]

Abstract

The effects of three irreversible anticholinesterase agents, echothiophate (217MI), tertiary methylamine analog of 217MI (217AO) and Tetram, on end plate currents (e.p.c.s) of Rana pipiens cutaneous pectoris muscle were studied using electrophysiological techniques. All three compounds (217MI, 1-10 microM; 217AO, 1-25 microM; and Tetram, 1-50 microM) decreased the rate of e.p.c. decay (alpha) to the same extent as neostigmine (10 microM), a reversible anticholinesterase agent. Decay remained a single exponential at all membrane potentials. 217MI and its derivatives greatly reduced the normal voltage dependence of alpha represented by the slope (H = mV-1) of log alpha vs. membrane potential, in contrast to neostigmine which had no effect on H. Suppression of Ach release by the addition of 4 mM Mg++ to end-plates did not alter the reduction of H by 217AO indicating that the anticholinesterase-induced decrease in H is not simply due to an increased interaction between Ach and its receptors. Additionally, the pretreatment of end-plates with methanesulfonyl fluoride, also an irreversible cholinesterase agent, did not modify the effects of 217AO and Tetram on H. 217MI and its derivatives, at low concentrations which altered H, did not affect [3H]PCP or [125I]alpha-bungarotoxin binding to Torpedo californica Ach receptor-rich membranes. It is concluded that these agents alter H by an effect on the Ach receptor ion channel complex unrelated to either esterase inhibition or channel block.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Echothiophate	Cholinesterase	Protein	Humans	Yes	Inhibitor	Details