Basic research study
Overexpression of endothelial nitric oxide synthase increases skeletal muscle blood flow and oxygenation in severe rat hind limb ischemia

Presented at the Forty-ninth Scientific Meeting of The American Association for Vascular Surgery and the Fifty-fifth Annual Meeting of The Society for Vascular Surgery, Baltimore, Md, June 9, 2001.
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Abstract

Objective

Although nitric oxide (NO) has a critical role in angiogenesis, the therapeutic potential of NO synthase overexpression in severe ischemia remains undefined. We tested the hypothesis that overexpression of endothelial NO synthase (eNOS) would improve tissue perfusion in severe hind limb ischemia.

Methods

Severe hind limb ischemia was induced in 122 adult male Sprague-Dawley rats. Ten days after the induction of hind limb ischemia, vascular isolation and intraarterial delivery of an adenoviral vector encoding eNOS (AdeNOS), a control adenoviral vector (AdE1), or phosphate-buffered saline solution (PBS) was performed. Skeletal muscle blood flow, muscle oxygen tension, angiography, and immunohistochemistry for capillary counts were measured.

Results

Gene transfer of AdeNOS increased eNOS protein expression and enzyme activity. Two weeks after gene transfer, skeletal muscle blood flow was fourfold higher in eNOS-transduced than in AdE1-transduced or PBS treated rats and was similar to exercise-induced maximal flow in nonischemic muscle. eNOS overexpression increased muscle oxygen tension in a titer-dependent fashion. This increase persisted 1 month after transduction, even though eNOS enzyme activity had declined to normal levels. Angiography and capillary counts showed that eNOS overexpression increased the size and number of collateral arteries, but did not significantly increase the capillary–muscle fiber ratio.

Conclusions

eNOS overexpression in an ischemic rat hind limb significantly increased skeletal muscle blood flow, muscle oxygen tension, and collateral arteries (arteriogenesis). Furthermore, eNOS overexpression did not result in capillary angiogenesis above control levels. These studies demonstrate the potential for eNOS overexpression as treatment for severe limb ischemia in human beings.

Cited by (0)

Supported by the William J. von Liebig Foundation (L.S.B.) and by National Institutes of Health Grant HL51184 (L.M.M.). Dr Brevetti is the recipient of a National Research Service Award (NIH) HL10253; Dr Sarkar is the recipient of a Mentored Clinical Scientist Development Award (HL04435) from the Lifeline Foundation and the National Heart, Lung and Blood Institute, National Institutes of Health.

Competition of interest: none.