Shown are vasoactive responses to EVA-1, capped EVA-1 (AP12A), P7 and P37 before (solid circles) and after (open circles) tissue bath exposure to the nitric oxide donor, SNP, for 2 minutes (10-4M). In each case, nitrosative stress induced a significant left shift in the concentration response curve. *differs from baseline state; significance level p<0.05.