Naunyn-Schmiedeberg's Archives of Pharmacology

, Volume 292, Issue 2, pp 161-165

First online:

125I-Labelled botulinum a neurotoxin: Pharmacokinetics in cats after intramuscular injection

  • H. WiegandAffiliated withPharmakologisches Institut der Justus Liebig-Universität
  • , G. ErdmannAffiliated withPharmakologisches Institut der Justus Liebig-Universität
  • , H. H. WellhönerAffiliated withPharmakologisches Institut der Justus Liebig-Universität

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  1. 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:

  1. a)

    A disto-proximal gradient of radioactivity (RA) had developed in the sciatic nerve of the injected side.

  2. 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.

  3. 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.

  4. 2.

    In histoautoradiographs of the (ligatured) ventral roots the RA was strictly confined to the intraaxonal space of a few nerve fibres.

  5. 3.

    On injection of equal doses of 125I-BTA into either gastrocnemius muscle we found after 38 h:

  1. a)

    Direct stimulation of only one of the injected muscles 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.

  2. 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.


Key words

Botulinum A toxin Pharmacokinetics Neural ascent Neuromuscular activity