Early inducible nitric oxide synthase 2 (NOS 2) activity enhances ischaemic skin flap survival.
A functional skin-flap model of angiogenesis in the mouse was utilized to investigate ischaemic flap survival/angiogenesis whilst under pharmacological or genetic inhibition of nitric oxide synthase (NOS). In this model, the epigastric artery was cauterized. Following a five-day angiogenic period an abdominal skin-flap supplied by the pre-existing epigastric artery was raised and resutured. After a further six days the outcome was determined by measuring the area of living skin-flap that was sustained by new vessel growth around the cauterized artery. Both pharmacological [ S-methyl-isothiourea (SMT) given via i.p. injection for the five-day angiogenic period] and genetic inhibition of NOS 2 (using NOS 2-/- mice) caused a similar and significant fall in flap survival compared to saline-treated wild-type mice ( P < 0.05). Delaying pharmacological NOS 2 inhibition for two days post-arterial cauterization increased flap survival in wild-type mice to that of saline-treated controls, whilst treating wild-type mice with SMT for only the first three days of angiogenesis produced a significant decrease in flap survival, similar to that of five-day SMT-treated wild types. Immunoreactivity for NOS 2 in NOS 2-/- knockout mice was absent in both pedicles and skin-flaps, whilst mast cells from both the pedicle and the skin-flap stained positively for NOS 2 in wild-type mice. Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF 2) immunoreactivity was also strongly evident in mast cells of both wild-type and NOS 2-/- mice at both sites. These results point to a significant role for NOS 2 in promoting wound healing/angiogenesis in its early stages.
Plastic and Reconstructive Surgery, Suwa Red Cross Hospital, Kogan-Douri, Suwa, Japan.
Sunao
S
Furuta
Peter
P
Vadiveloo
Rosalind
R
Romeo-Meeuw
Wayne
W
Morrison
Alastair
A
Stewart
Geraldine
G
Mitchell
D000818:Animals; D002451:Cell Compartmentation; D002470:Cell Survival / Q000502:physiology*; D019074:Epigastric Arteries / Q000293:injuries; D016222:Fibroblast Growth Factor 2 / Q000032:analysis; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D007511:Ischemia / Q000473:pathology*; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D018919:Neovascularization, Physiologic; D019001:Nitric Oxide Synthase / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II; D012867:Skin / Q000098:blood supply / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis; D014945:Wound Healing
D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse