Abstract

The action of d-tubocurarine (dTC) on the motor nerve terminal (m.n.t.) was observed by noting the effects of dTC on posttetanic repetitive activity (PTR) in the cat soleus nerve. PTR is a neural phenomenon; it is generated in the m.n.t. entirely by a neural mechanism. Therefore, drugs affecting PTR necessarily act on the m.n.t. dTC in a dose of 10 µg/kg i.a. abolished PTR in every experiment. This dose has no appreciable effect on the isometric twitch tension of the indirectly stimulated soleus muscle. The remarkable sensitivity of the m.n.t. suggests that it is a principal site of dTC action and that prejunctional drug action may contribute to the blockade of neuromuscular transmission.