Succinylmonocholine Iodide: Its Enzymatic Hydrolysis and Neuromuscular Activity.

Abstract

The enzymatic hydrolysis of succinylmonocholine iodide (SMC-J) was compared to that of succinyldicholine dichlo-ride (SDC-C12) in 3 human plasmas by Warburg''s manometric technique. In the 1st hr. the hydrolysis rate of SDC-Cl2 was 8 times greater than that of SMC-J. The CO2 produced by the hydrolysis of equal concns. of SMC-J and SDC-Cl in the 1st hr. was the same as that produced by the dicholine component alone. The hydrolysis of SDC-Cl in heat inactivated plasma was considerable, that of SMC-J negligible in the 2 hr. observation period. In the sciatic gastrocnemius prepn. of cats, 1 mg./kg. SMC-J caused an incomplete neuromuscular block; a 2.5 mg./kg. dose caused a complete block. Repetition of the 1 mg./kg. dose at 20 min. intervals showed a marked cumulative effect. The effects of SMC-J and SDC-C12 on neuromuscular transmission were additive.