title: Effects of succinylcholine chloride on the response of fast and slow muscle in the cat.
abstract: Fast and slow muscle fibres differ histochemically, electrophysiologically and pharmacologically. In vivo, the effect of 0.05, 0.075 and 0.1 mg X kg-1 succinylcholine on the response of the indirectly stimulated gastrocnemius (fast) and soleus muscle (slow) to single, train-of-four and tetanic stimuli was studied. There was a significant difference between the response of the two muscles. Maximum twitch suppression occurred 2 min after injection and was more significant in the gastrocnemius than the soleus. The duration of the neuromuscular blockade was 9 min or more in both groups. The train-of-four ratio dropped below 0.7 in the gastrocnemius preparation at all doses and in the soleus when 0.1 mg X kg-1 succinylcholine was used. Sustained tetanus was achieved in both muscles at 5 and 10 min, respectively. There was evidence of fatigue in the soleus muscle at the 5-min observation suggestive of the presence of a phase II block, a phenomenon not observed in the gastrocnemius.
mesh_terms: D000771:Anesthesia, Intravenous; D000818:Animals; D002415:Cats; D004558:Electric Stimulation; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects* / Q000502:physiology; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000502:physiology; D010424:Pentobarbital; D013390:Succinylcholine / Q000494:pharmacology*; D009435:Synaptic Transmission; D013997:Time Factors
chemical_list: D010424:Pentobarbital; D013390:Succinylcholine