The effects of botulinum toxin A on the survival of a random cutaneous flap.
BACKGROUND
Although interest in flap surgery has increased, a satisfactory research study on supportive drugs or methods for flap surgery has not been seen in the literature thus far. Despite several studies using botulinum toxin A for flap surgery being reported, their efforts to clarify the mechanisms are not sufficient. Therefore, the authors have studied the effect of botulinum toxin A on random cutaneous flap survival in a rat model under the hypothesis that it affects the microvascular system.


METHODS
Thirty 10-week-old Sprague-Dawley rats were divided into experimental (n=15) and control groups (n=15). The experimental group used 1.5 IU (International Units) of botulinum toxin A, and the control group used normal saline. A 2x8 cm random cutaneous flap was designed on the rats and then elevated. Normal saline (0.05 cc) and 1.5 IU of botulinum toxin A (0.05 cc) (Botox, Allergan, USA) were injected into the dermis layer of the central portion in the proximal one-third of the flap. Gross photographs were taken at days 1, 3, 5 and 7 after the operation. Laser-induced fluorescein fluoroscopy was performed on postoperative day 7 and tissues were retrieved for histological analysis. In addition, reverse transcriptase polymerase chain reaction (RT-PCR) was carried out for quantitative analysis.


RESULTS
Gross photos and laser-induced fluorescein fluoroscopy reveal the survival rate of the Botox group was 8.3% higher than the control. In the histologic study, the diameter of vessels is larger and the number of immature vessels is more in the Botox group. The result of RT-PCR shows increased expression of VEGF (vascular endothelial growth factor), CD 31 (PECAM1, platelet/endothelial cell adhesion molecule) and iNOS (inducible nitric oxide synthase), which are considered to be related to vasodilation and endothelial proliferation.


CONCLUSIONS
Our results suggest that botulinum toxin A increases the survival rate of random cutaneous flaps by means of selective suppression of sympathetic neurons of the cutaneous microcirculation system.
Kim
Taek Kyun
TK
Department of Plastic and Reconstructive Surgery, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.
Oh
Eun Jung
EJ
Chung
Jae Young
JY
Park
Jae Woo
JW
Cho
Byung Chae
BC
Chung
Ho Yun
HY
D000818:Animals; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D005471:Fluoroscopy; D006085:Graft Survival / Q000187:drug effects*; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013524:Surgical Flaps / Q000098:blood supply*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D009465:Neuromuscular Agents; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D042461:Vascular Endothelial Growth Factor A; D052247:Nitric Oxide Synthase Type II; D019274:Botulinum Toxins, Type A