The nature of suxamethonium neuromuscular block in the dog assessed by train-of-four stimulation.
Evoked muscle responses from continuous train-of-four (frequency 2Hz) electrical nerve stimuli, with an interval of 10 sec between each train, were recorded in the intact anaesthetised dog receiving multiple doses of suxamethonium at 0.035 mg/kg. The train-of-four twitches showed a slight progressive fade from the first to the fourth and this fade increased as additional doses of the muscle relaxant were given. The train-of-four ratio was used to divide the suxamethonium neuromuscular block into phase 1 and phase 2 components. Dogs receiving one dose of suxamethonium at 0.3 mg/kg were developing the phase 2 block during the return of neuromuscular activity and after the third to fourth dose this block was fully established. Evidence of tachyphylaxis was present in the phase 1 block which persisted into the phase 2 component.
D000818:Animals; D004285:Dogs; D004558:Electric Stimulation / Q000379:methods*; D005260:Female; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000502:physiology; D013390:Succinylcholine / Q000008:administration & dosage / Q000494:pharmacology*
D013390:Succinylcholine