Figure 6.

Low concentrations of NO are proangiogenic. A: RENCA cells (2 × 10⁶) were injected into the flanks of BALB/c mice. After 14 days (day 1 in graph), tumors became visible and/or palpable. Increasing concentrations of the NO donor NOC-18 were then injected every 3–4 days into the center of the tumor in a minimal volume. Tumor growth rate was calculated as described previously (n = 4 in each group). **P < 0.01 relative to PBS; ^†P < 0.05, ^††P < 0.01 relative to NOC-18 at 0.5 μg/ml. B: Silicon tubes were filled with PBS (negative control, NC), a mixture of FGF-2 (30 ng/μl) and vascular endothelial growth factor (0.1 ng/μl) (positive control, PC), or with increasing amounts of NOC-18, all mixed with basement membrane extract. The tubes were implanted subcutaneously into the flanks of BALB/c mice, removed after 17 days, and photographed (n = 4).