Figure 4. Western blot analysis of eNOS (upper part) and iNOS (lower part) proteins obtained from human healthy (A) and hyperemic (B) dental pulp, as well as from the pulp with irreversible pulpitis (C). The pulpal proteins were stained by antibodies against human eNOS antigen (133 kD) and iNOS antigen (130 kD). ß-actin is used for control. All 3 groups contain the eNOS enzyme, with the highest amount in the hyperemic group. The iNOS protein was undetectable in the healthy group. A significant increase of iNOS enzyme was observed in the hyperemic and the irreversible pulpitis groups. The panels at right show the densitometric analysis of eNOS (upper part) and iNOS (lower part) protein bands. Data are expressed as means ± SD of 5 pulps in each group. The differences of integrated optical density (IOD) of eNOS and also iNOS bands, indicated in Table 3 (Appendix), were significant in all 3 groups (*p < 0.05, A vs. B; *p < 0.05, B vs. C; *p < 0.05, A vs. C in both cases).