Representative tracing of formyl peptide from bacteria (FMLP)-induced relaxation in isolated resistance arteries (third order mesenteric arteries) from Wistar rats. The segments were initially contracted with phenylephrine (PE, 10 μM). Subsequently, FMLP (N-formyl–methionyl–leucyl–phenylalanine, 10 or 30 μM) was added in the absence or presence of cyclosporin H (FRP antagonist: CsH, 1 μM). As shown in (A), both concentrations of FMLP (10 or 30 μM) induced relaxation, and the pre-incubation with CsH inhibited this response (B). Wire myograph was used to analyze vascular function.