Blockade of electrophysiological properties of muscle fibres by lycorine.

This study concerns the action of the alkaloid lycorine on electrophysiological properties of single sartorius muscle fibres. Lycorine caused a decrease of the resting membrane potential, a lengthening in the rise and decay times of the action potential and a fall of the muscle accommodation. The depolarizing effect was not affected when Na+ is replaced by choline in the Ringer solution. Lycorine did not inhibit the (Na+ + K+) ATPase activity. The results suggest that action of lycorine on the electrophysiological properties can be attributed to an interference with potassium channels.