SUCCINYLCHOLINE AND VECURONIUM BLOCKADE OF THE DIAPHRAGM, LARYNGEAL AND LIMB MUSCLES IN THE ANESTHETIZED GOAT

The purpose of the study was to compare the response of the cricoarytenoideus dorsalis muscle (CD) to neuromuscular blocking drugs with those of the thyroarytenoideus (TA), diaphragm (DI) and ulnaris lateralis (UL) muscles. Evoked electromyographic response to indirect supramaximal stimulation at 1 Hz was monitored in ten adult goats under thiopentone-halothane anaesthesia. The onset time and duration of neuromuscular blockade after intravenous administration of 500 mu g(.)kg(-1) of succinylcholine or 4 mu g(.)kg(-1) of vecuronium were determined. Times to 100% paralysis in CD, TA, DI and UL after succinylcholine were (mean +/- SD) 39 +/- 11, 39 +/- 11, 42 +/- 8 and 57 +/- 8 seconds, respectively; the corresponding times for vecuronium were 5.6 +/- 2.3, 4.6 +/- 1.7, 6.0 +/- 1.9 and 9.6 +/- 1.7 min. The order of recovery to 25% spontaneous EMG activity was TA, CD, DI and UL after succinylcholine (durations: 9.7 +/- 3.6, 11.0 +/- 3.0, 15.3 +/- 1.3 and 22.0 +/- 1.2 min, respectively) but DI, CD, TA and UL after vecuronium (durations: 31.9 +/- 18.6, 35.2 +/- 19.5, 47.1 +/- 19.9 and 71.7 +/- 16.1 minutes, respectively). Thus, as in the diaphragm and thyroarytenoideus muscles, onset time and duration of succinylcholine or vecuronium blockade were shorter in the abductor muscle of the glottis, cricoarytenoideus dorsalis, than in the limb muscle.