CHARACTERISTICS of muscular contraction induced by magnetic stimulatio
n were studied using isolated gastrocnemius muscles of a frog. The fig
ure-eight coil position was regarded as 0 degrees when the direction o
f induced current was parallel to the muscle fiber axis, and 90 degree
s when the induced current was perpendicular to the muscle fiber axis.
Muscular contraction readily occurred with lower outputs of magnetic
stimulation at 0 degrees and 180 degrees, but it was weak at 90 degree
s and 270 degrees. Magnetic stimulation did not directly induce muscul
ar contraction but it acted on the synapses forming end plates to musc
le cells, and muscular contraction occurred if the direction of the ed
dy current was parallel to the nerve which innervated the muscle cells
. (C) 1998 Lippincott Williams & Wilkins.