Potency (pEC50) and maximum response (Emax) values derived from concentration-response curves to the PDE5 inhibitors sildenafil, vardenafil, and tadalafil (0.0001-10 μM each) in endothelium-intact (E+) or denuded (E−) rat aortic rings contracted with phenylephrine (0.1-1 μM)
Curves were performed in the absence and in the presence of the NO scavenger carboxy-PTIO (100 μM). Data represent the mean ± S.E.M. of six experiments.
E+ | E− | |||||
|---|---|---|---|---|---|---|
| pEC50 | Emax | pEC50 | Emax | |||
| Sildenafil | 8.10 ± 0.04 | 95 ± 1 | 6.44 ± 0.06 | 59 ± 7 | ||
| +PTIO | 7.36 ± 0.12* | 55 ± 4* | 6.21 ± 0.14 | 43 ± 8 | ||
| Vardenafil | 8.53 ± 0.06 | 100 ± 1 | 6.07 ± 0.07 | 99 ± 3 | ||
| +PTIO | 7.21 ± 0.16* | 99 ± 1 | 5.98 ± 0.06 | 95 ± 2 | ||
| Tadalafil | 8.01 ± 0.04 | 97 ± 1 | 6.72 ± 0.11 | 48 ± 6 | ||
| +PTIO | 7.24 ± 0.12* | 56 ± 5* | 6.60 ± 0.12 | 40 ± 5 | ||
↵* P < 0.01 compared with the respective control values.