MAMMARY ARTERY VERSUS SAPHENOUS-VEIN GRAFTS - ASSESSMENT OF BASIC FIBROBLAST GROWTH-FACTOR RECEPTORS

Neointimal hyperplasia limits the long-term patency of saphenous vein grafts (SVGs), but is notably absent from most internal mammary artery (IMA) grafts. Basic fibroblast growth factor (bFGF) is a local endoth elial and vascular smooth muscle mitogen known to be involved in the p athogenesis of neointimal hyperplasia. This study used an animal model to compare the number of available high-affinity (HAR) and low-affini ty (LAR) bFGF receptors in SVGs and IMA grafts and to determine whethe r distention injury causes an increase in receptor availability. The I MA and SVG specimens were harvested from 12 dogs and distended at 25 o r 200 mm Hg for 15 minutes, and then the bFGF receptor uptake was meas ured in them using iodine 125-labeled bFGF. In the IMA conduits disten ded at low pressure, there were 2.54 +/- 0.10 (mean +/- standard error of the mean) HARs per mm(2) of intimal surface area available and 5.1 9 +/- 0.40 LARs per mm(2). High-pressure distention significantly (p < 0.001) increased the number of available HARs to 5.06 +/- 0.27 per mm (2) and of LARs to 7.27 +/- 0.042 per mm(2). At low pressure, the SVGs had significantly (p < 0.001) more HARs (9.14 +/- 0.84 per mm(2)) and LARs (18.2 +/- 0.57 per mm(2)) available than did the IMA conduits, a nd high pressure significantly (p < 0.001) increased the number of HAR s available in SVGs to 24.1 +/- 2.43 per mm(2) and the number of LARs to 44.7 +/- 2.34 per mm(2). These results demonstrate that there is a significantly higher number of available bFGF receptors per unit of su rface area in dog SVGs than IMA grafts. High-pressure distention furth er increases the differences in the number of available bFGF receptors between SVGs and IMA grafts (p < 0.001). These findings suggest a new ly recognized mechanism that may contribute to the increased intimal h yperplasia found in implanted SVGs but not IMAs.