DIRECT ACTION OF 4‐AMINOPYRIDINE ON THE CONTRACTILITY OF A FAST‐CONTRACTING MUSCLE IN THE CAT

1. The effects of 4-aminopyridine on the contractility of the fast-contracting tibialis anterior and the slow-contracting soleus muscles of cats under chloralose anaesthesia have been studied. 2. 4-Aminopyridine, in doses of 0.5 mg/kg and above, produced a slowly developing increase in the twitch tension of directly stimulated chronically denervated and of indirectly stimulated innervated tibialis anterior muscles, but had little or no effect …