EFFECTS OF QUININE ON MAMMALIAN SKELETAL MUSCLE

Abstract

Quinine in small doses increases the response of a muscle to slow rates of direct or indirect stimulation while depressing the response to high rates of stimulation. With increasing doses of quinine the rate of stimulation required to show depression decreases, and finally depression is evident at all rates of stimulation. Larger doses of quinine are required to produce the depression in directly stimulated muscles than in indirectly stimulated muscles; the probable explanation for this is discussed. Quinine antagonizes the actions of eserine on skeletal muscles as effectively as, and in some instances more effectively than, curare. Eserine is, however, not as effective in antagonizing the actions of quinine as it is in antagonizing the actions of curare. Quinine inhibits the fibrillation of denervated muscle but an attempt to inhibit the atrophy of denervation in the gastrocnemius-soleus muscle of the white rat was unsuccessful. The prolonged first response to electrical stimulation which a denervated muscle shows and which has many properties in common with myotonic contractions is inhibited by quinine.