The effect of thermolysin (0.01–1 u ml−1, 20 min) on relaxations to (a) trypsin, (b) thrombin, (c) SLIGRL-NH2, (d) SFLLRN-NH2, (e) substance P and (f) bradykinin in endothelium-intact, U46619-contracted pig coronary artery ring segments. Cumulative concentration-response curves were generated in the absence (control), presence, and after washout of thermolysin. Data are mean±s.e.mean from 4–8 experiments and are expressed as a percentage of the maximum relaxation to isoprenaline (1 μM). *P<0.05 (t-test) for pEC50 values for bradykinin in the presence of thermolysin vs after thermolysin washout.