FIG. 8.
The M1 receptor is not important to carbachol-induced pulmonary arterial contraction. Dose–response curves of pulmonary arterial rings to 1 nm–100 μM carbachol (CCh) added in a cumulative manner normalized to %TKmax following addition of 100 nM pirenzepine for adult normoxic (A), adult hypoxic (B), and fetal normoxic (C) animals. The control response is depicted with filled black circles and a solid line, while the pirenzepine response is depicted with filled gray squares and a dashed line. Lines show resultant fits with a Hill equation to the dose–response relationships, and markers show mean ± SEM. The data were analyzed by two-way ANOVA with a Bonferroni post-test analysis for each dose compared to control. No significant differences were observed. PIR data are based on 16 adult normoxic arteries (5 animals), 14 adult hypoxic arteries (5 animals), and 14 fetal normoxic arteries (5 animals).