Figure 4 - Concentration-response relationship for Pseudomonas aeruginosa lipopolysaccharide in canine renal arteries (N = 6). Segments were contracted with 2 ÁM prostaglandin F2a (PGF2a) (initial tension) and exposed to increasing concentrations of endotoxin (0.05-0.50 mg/ml). Results are reported as means ▒ SEM. *P<0.05 compared to the initial tension of arterial segments with endothelium (Student t-test). +P<0.05 compared to initial tension of arterial segments without endothelium (Student t-test).