Segments of porcine saphenous veins (n=3–15) were either left untreated (Ctrl), marked with a surgical skin marker (SSM) or a solution of FCF (2.6 mM, in 5% propylene glycol and water) with a cotton swab in a longitudinal line and incubated in at room temperature in PlasmaLyte for 15min, or treated with 50% isopropanol (IPA) or 1% methlyene blue (MB) for 15 min treated Segments were then incubated, cut into rings, suspended in a muscle bath and treated with KCl (110 mM). Force generated was converted to stress. The error bars show the standard deviation. *P< 0.05 in paired t-tests.