BACKGROUND: Succinylcholine (Sch) has been generally reported not to produce tetanic stimulation fade on train of four in phase I block, except phase II block. But, the prejunctional phenomenon of Sch during onset is rarely reported these days, and so we investigated whether the prejunctional phenomenon of Sch during onset exists in cats.

METHODS: We checked train of four ratios (TOF-R) and tetanic fade ratios (TF-R) by using a nerve stimulator before and after 50 µg/kg of Sch less than ED95 was administered, and during recovery in anesthetized cats. We analyzed TOF-R and TF-R before drug administration as a control and during onset and recovery time in order to estimate the statistic significance of fade.

RESULTS: TOF fade and tetanic stimulation during the onset of Sch appeared like those in the partial block of nondepolarizing neuromuscular blockades TOF-R and TF-R during Sch onset compared with those in control and recovery time of Sch had statistical significance (P < 0.05).

CONCLUSIONS: The prejunctional phenomenon appeared only during Sch onset in cats and then disappeared during recovery to the control level.