Abstract
1. The effects on the membrane activities of the toad sartorius muscle of veratrine, aconitine, veriloid, calcium-free solution, guanidine, TEA, quinine, caffeine, excess of K+ ion, procaine and CuO+ ion were investigated with an intracellular recording electrode.
2. Veratrine produced repetitive muscle spikes when single shock stimulation was applied either to the nerve or muscle.
Veriloid, aconitine and calcium-free solution have been observed to produce such repetitive responses.
Guanidine produced repetitive muscle spikes only if a motor nerve volley was applied.
3. Veratrine, aconitine, veriloid, guanidine, quinine, TEA and procaine did not alter the resting potential. Excess of K+ ion, caffeine and CuO+ ion produced a marked fall in the resting potential.
4. Veratrine, aconitine, TEA and guanidine increased the size of the e.p.p. in the low-sodium muscle, whereas caffeine, quinine, veriloid and CuO+ ion decreased it. Procaine was ineffective or only slightly diminished the size.
