Microscopic technique for the detection of nitric oxide-dependent angiogenesis in an animal model

Nitric oxide (NO) plays an important role in maintaining vascular homeostasis. The importance of NO in the vasculature is demonstrated by several experimental conditions, such as vascular endothelial growth factor (VEGF)-induced angiogenesis. Thus, the NO metabolic pathway in endothelial cells could be one of the main contributing factors for angiogenesis. Although several methods have been used for measuring in vitro angiogenesis, a proper technique has not been developed for identifying in vivo NO-dependent angiogenesis. This chapter provides a new intravital microscopic method for detecting and measuring NO-dependent angiogenesis in a mouse model. This technique showed strong abdominal neovascularization in wild-type mice, but not eNOS knockout mice, locally injected with VEGF, as well as stimulation of angiogenesis in NO donor-injected mice. This technique also revealed the inhibitory effect of the NOS inhibitor N(G)-iminoethyl-L-ornithine in VEGF-mediated in vivo angiogenesis. This chapter describes intravital microscopy as a new imaging technique for detecting NO-dependent angiogenesis in an animal model.