The effects of botulinum toxin type A on muscle blood perfusion and metabolism.
BACKGROUND
Botulinum toxin type A is approved by the U.S. Food and Drug Administration for the treatment of facial rhytides. However, the complete spectrum of action of botulinum toxin A has not yet been completely defined. Little is known about the metabolism of muscle after botulinum toxin A injection. This information may give insight into the additional effects botulinum toxin A may have on muscle. The authors assessed the influence of botulinum toxin A on the metabolism of muscle using dynamic investigative techniques.


METHODS
Twenty New Zealand White rabbits were divided into control, paralysis, and sham groups. Masseter muscle paralysis was achieved with botulinum toxin A. Dynamic computed tomographic and positron emission tomographic scans were obtained. Masseter muscle blood flow, blood volume, permeability surface, and mean transit time and glucose uptake were measured.


RESULTS
Eighteen animals completed the study. Masseter blood perfusion showed consistent results across all parameters. Blood flow, blood volume, and permeability surface were significantly increased at weeks 4 and 8 on the paralyzed side. Mean transit time at week 4 was decreased on the paralyzed side. Positron emission tomographic scans showed that injected muscles in the botulinum toxin A group tended to have increased glucose uptake compared with untreated muscles.


CONCLUSIONS
Botulinum toxin A injection increases muscle blood perfusion parameters and glucose uptake for a transient period. This increase is similar in duration to the known interval of botulinum toxin A-induced paralysis. These changes have been identified in a dynamic fashion and may represent changes in calcitonin gene-related peptide release.
Matic
Damir B
DB
London, Ontario, Canada From the Division of Plastic and Reconstructive Surgery and Department of Medical Biophysics, University of Western Ontario.
Lee
Ting Y
TY
Wells
R Glenn
RG
Gan
Bing S
BS
D000818:Animals; D001810:Blood Volume / Q000187:drug effects; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000494:pharmacology*; D002199:Capillary Permeability / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism / Q000493:pharmacokinetics; D021621:Imaging, Three-Dimensional; D007273:Injections, Intramuscular; D008406:Masseter Muscle / Q000098:blood supply / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000378:metabolism; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000494:pharmacology*; D009929:Organ Size / Q000187:drug effects; D049268:Positron-Emission Tomography; D011817:Rabbits; D011897:Random Allocation; D012039:Regional Blood Flow / Q000187:drug effects; D016037:Single-Blind Method; D014057:Tomography, X-Ray Computed
D009465:Neuromuscular Agents; D019788:Fluorodeoxyglucose F18; D019274:Botulinum Toxins, Type A