The Effect of Obidoxime on Reversal or Prevention of Paraoxon-Induced Changes in the Function of Chick Biventer Cervices Nerve-Muscle Preparation

Aims. Paralysis of skeletal muscles, which can lead to paralysis of respiratory muscles and death, is one of the most toxic effects of organophosphates (OPs), and oximes are the only available antidotes that can reverse or prevent such toxic effects. In the present study, the possible reversal or preventive effect of different concentrations of obidoxime (toxogonin) on changes induced by paraoxon (as an OP) on the function of skeletal muscles was investigated in chicken biventer cervices nerve-muscle (CBC) preparation using the twitch tension recording technique. Methods. Twitches of the CBC muscle were evoked by stimulating the motor nerve at 0.1 Hz with pulses of 0.2 msec duration and a voltage of greater than that required to produce the maximum response. Twitches were recorded isotonically using Narco Biosystems. Previous studies indicate that paraoxon at 100 nM induces a significant increase (more than 100%) in the twitch amplitude therefore, this concentration was used to examine the possible capability of obidoxime to reverse or prevent such effects. Results. Obidoxime at 300 m M could almost fully reverse (when used as post treatment) or prevent (when used as pretreatment or at the same time as toxin) the effect of paraoxon. However, oxime at, 10, 30 and 100 m M could only reverse or reduce this effect to about 30-80%. Oxime alone had also no significant effect on the function of the muscle at concentrations used. Conclusion. These data suggest that obidoxime alone may fully reverse the effect of paraoxon on skeletal muscle tissues.