Relaxation responses of pulmonary arteries to phenylephrine.
Concentration-response curves to phenylephrine in segments of pulmonary arteries (a and b) from rats (N = 5–7). The number of rats is the number of repetitions of each group. After pretreatment with receptor antagonists (5 × 10 − 6 M propranolol and 2 × 10 − 5 M prazosin) or inhibitors (2 × 10 − 4 M N[gamma]-nitro-L-arginine methyl ester [L-NAME]) for 30 min, constriction of all arteries was induced with U46619, arteries then were exposed to increasing concentrations of phenylephrine except sham group. Control group was exposed to phenylephrine without any pretreatment. Asterisk indicates significance compared to the sham group. Hashtag indicates significance compared to the control group. “*” means p < 0.05; “**” means p < 0.01; “***” means p < 0.001; “#” means p < 0.001. (one-way analysis of variance, Bonferroni post hoc comparison)