Instillation of diesel exhaust particles (DEP) has no effect on vascular responses ex vivo. (a) Contraction to phenylephrine (PE), and relaxation to (b) acetylcholine (ACh), (c) sodium nitroprusside (SNP) and (d) isoprenaline (ISP) in the thoracic aorta. Responses to ACh in (e) femoral artery and (f) 3rd order mesenteric arteries. Data from saline-instilled animals (open symbols) and DEP-instilled animals (closed symbols) sacrificed at 6 h (circles, solid line) or 24 h (triangles, dashed line) after instillation. Results are expressed as mean ± SEM (n = 6-10). No significant differences were found between saline or DEP instilled animals at either time points for all vessels (two-way ANOVA).