[Neuromuscular blocking and respiratory depressing actions of sodium ammonium dimethyl-2-(propano-1,3-dithiosulfate) monohydrate].

The neuromuscular blocking and respiratory depressing actions of the new insecticide sodium ammonium dimethyl-2-(propano-1,3-dithiosulfate) monohydrate (SCD) were investigated. In peroneal-tibialis anterior nerve-muscle preparations of urethane anesthetized rabbit, SCD 6.5 mg/kg iv completely depressed the indirectly elicited twitch tension but not the directly elicited one. This compound also caused initial potentiation of the indirectly elicited twitch tension. In the partially paralyzed preparations, potentiation of contractions occurred following a brief period of indirectly tetanic stimulation. Nereistoxin but not SCD blocked the indirectly elicited twitch tension of isolated rat diaphragm. The neuromuscular blockade induced by SCD and nereistoxin was antagonized by neostigmine and 4-aminopyridine. SCD and nereistoxin had little or no effect on arterial blood pressure and phrenic nerve discharge of rabbits. The results indicated that SCD-poisoned rabbits died of respiratory paralysis following the neuromuscular blockade.