Potentiation by gentamicin of non-depolarizing neuromuscular block in the cat

Gentamicin 1-5 mg/kg was injected into 14 anaesthetised cats in the presence of a constant, partial, non-depolarizing neuromuscular block. Twitch response in tibialis anterior was significantly depressed from 83% to 71% of control by a dose of 1.0 mg/kg. In soleus the same dose reduced twitch response from 76% to 71%. After a cumulative dose of 10 mg/kg twitch response in tibialis anterior and soleus was 34% and 37% of control respectively. Calcium chloride 20 mg/kg restored twitch response to 66% in both muscles. Smaller doses of calcium chloride caused partial reversal which was maintained for five minutes in only 50% of instances.