Pig saphenous veins were either untreated (ctrl; n=5–10) or stretched to twice their resting length (stretched; n=10). Stretched segments were then either left untreated, marked with a solution of FCF (2.6 mM, in 5% propylene glycol and water) using a cotton swab in a longitudinal line, or treated in 50μM brilliant blue G (BBG) or 50μM Allura red (Red). The segments were then incubated at room temperature for 15 min in PlasmaLyte and cut into rings, suspended in a muscle bath and treated with KCl (110 mM). Force generated was converted to stress. Results are presented as mean±SD. *P< .05, **P<.005 in paired t-tests.