INDUCIBLE NITRIC-OXIDE SYNTHASE EXPRESSION IN HUMAN VEIN GRAFTS

BACKGROUND: The patency of vascular reconstructive procedures is limit ed by the development of intimal hyperplasia (IH). Nitric oxide (NO) s eems to be beneficial in abrogating this process. Currently, there is little information concerning inducible nitric oxide synthase (iNOS), the enzyme responsible for NO synthesis, and human vein grafts. The pu rpose of this study was to examine iNOS gene expression in human aorto coronary vein grafts (ACVG) and infrainguinal vein bypass grafts (IVG) . METHODS: Nonthrombosed sections from ACVG (n = 5), IVG (n = 5), and control saphenous vein (SV; n = 4) were harvested and processed for RN A isolation. Quantitative reverse transcription-polymerase chain react ion (RT-PCR) was performed on samples using P-32 radioactively end lab eled primers. Glyceraldehyde-3-phosphate-dehydrogenase (GAPDH) was the internal control, and results were expressed as iNOS pmol/GAPDH pmol. RESULTS: There was a significant increase in the iNOS gene expression in the ACVG (0.049 +/- 0.01) when compared with IVG (0.019 +/- 0.001) or normal SV (0.011 +/- 0.002; P less than or equal to 0.05). There w as no significant difference between normal vein and the infrainguinal grafts. Sequencing of a fragment of the amplified 428 bp gene product confirmed 84% homology with the available gene bank human sequence. C ONCLUSIONS: This study proves that iNOS is expressed in human vein byp ass grafts. Additionally, there is a significant elevation of iNOS mes sage in human ACVGs compared with IVG or normal SV. This difference ma y be the result of the unique vascular beds supplied by these grafts. Ultimately, manipulation of iNOS expression may lead to therapies to a lleviate IH in these grafts. (C) 1997 by Excerpta Medica, Inc.