The effect of oxytocin on porcine malignant hyperpyrexia susceptible skeletal muscle.

1. Certain commercial preparations of oxytocin have been reported to reverse the development of pale soft exudative meat and malignant hyperpyrexia (MH) in pigs in vitro. 2. In this study it is shown that preservative-free oxytocin has no significant effect on the characteristic contractures of MH susceptible (MHS) muscle to halothane, caffeine, succinylcholine and KCl in vitro. 3. Whilst a commercial preparation of oxytocin, Syntocinon (containing chlorbutol as preservative), reversed and prevented the MHS characteristic responses, this study demonstrates conclusively that this was entirely due to the preservative chlorbutol.