Effects of Succinylcholine Chloride on the Response of Fast and Slow Muscle in the Cat

Publisher Website
Google Scholar
Abstract
Fast and slow muscle fibres differ histochemically, electrophysiologically and pharmacologically.In vivo, the effect of 0.05, 0.075 and 0.1 mg . kg‐1succinylcholine 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‐kg‐1succinylcholine 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.