The influence of skeletal muscle reinnervation on experimentally induced myotonia.
Earlier studies have shown that prior denervation of muscle prevents myotonia induced by 2,4-dichlorophenoxy acetic acid (2,4-D) both in vivo and in vitro. This work studied the effect of reinnervation on 2,4-D myotonia. Twenty Sprague-Dawley rats were injected with 2,4-D at specific intervals following unilateral sciatic nerve crushing; the gastrocnemius muscle on both sides was studied electromyographically to assess myotonia and to document denervation and reinnervation. All the rats gradually became amyotonic following denervation; myotonia reappeared during reinnervation. Myotonic discharges were no longer detectable 1 week after nerve crushing, but returned completely within 3 weeks. Blocking axoplasmic transport with colchicine had essentially the same effect on myotonia. A reciprocal temporal relationship was noted between the occurrence of fibrillations and myotonic discharges. These findings substantiate the view that innervation is essential to maintain the muscle membrane in a state that will support myotonic discharges.
Al-Sulaiman
A
A
Al-Rajeh
S
S
Iyer
V
V
D015084:2,4-Dichlorophenoxyacetic Acid; D000818:Animals; D001370:Axonal Transport; D002463:Cell Membrane Permeability; D004195:Disease Models, Animal; D004576:Electromyography; D008297:Male; D009132:Muscles / Q000294:innervation*; D009222:Myotonia / Q000139:chemically induced* / Q000503:physiopathology; D011188:Potassium / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism
D015084:2,4-Dichlorophenoxyacetic Acid; D012964:Sodium; D011188:Potassium