ELECTRICAL AND MECHANICAL ACTIVITIES OF THE RETRACTOR PHARYNX MUSCLE OF A SNAIL

Abstract

The relationship between mechanical and electrical activities of the snail retractor pharynx muscles has been studied. The magnitude of mechanical and electrical responses became larger with an increase in stimulus intensity, and the electrical responses have a linear relationship with the logarithm of tension developed. There is clear evidence of facilitation of the muscle contraction by indirect and direct stimulation after a conditioning stimulus. The interval of 2 stimuli to produce maximum facilitation is about 20-60 msec. The n.j.p. s were summed and potentiated by repetitive indirect stimuli and these reached a maximum at a frequency of 50/sec. The maximum contractions are produced by repetitive stimuli of 50/sec (indirect stimulation) and 30-50/sec (direct stimulation).