title: 125I-labelled botulinum A neurotoxin: pharmacokinetics in cats after intramuscular injection.
abstract: 1. On unilateral injection of sublethal doses of 125I-botulinum A neurotoxin (BTA) into one gastrocnemius muscle of the cat we found after 48 h: a) A disto-proximal gradient of radioactivity (RA) had developed in the sciatic nerve of the injected side. b) The ventral roots of the spinal cord half segments supplying the injected muscle showed a higher RA than the ventral roots of the contralateral control side. c) The spinal cord half segments innervating the injected muscle had a RA much higher than the corresponding segments of the contralateral side. However, a small rise of RA was also observed in the contralateral half segments. 2. In histoautoradiographs of the (ligatured) ventral roots the RA was strictly confined to the intraaxonal space of a few nerve fibres. 3. On injection of equal doses of 125I-BTA into either gastrocnemius muscle we found after 38 h: a) Direct stimulation of only one of the injected muscle caused the RA to reach a higher level in the spinal cord half segments ipsilateral to the stimulated muscle than in the spinal cord half segments of the non-stimulated side. b) Unilateral stimulation of one gastrocnemius nerve under the influence of gallamine or unilateral antidromic stimulation of the dorsal roots L7, S1 failed to cause a difference in RA between stimulated and non-stimulated side.
mesh_terms: D000818:Animals; D001370:Axonal Transport; D001905:Botulinum Toxins / Q000008:administration & dosage / Q000378:metabolism*; D002415:Cats; D004558:Electric Stimulation; D005260:Female; D007273:Injections, Intramuscular; D007700:Kinetics; D008297:Male; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology; D012584:Sciatic Nerve / Q000378:metabolism / Q000502:physiology; D013116:Spinal Cord / Q000378:metabolism; D013126:Spinal Nerve Roots / Q000378:metabolism
chemical_list: D001905:Botulinum Toxins