FIG. 7.
The M3 receptor is important to carbachol-mediated contraction in pulmonary arteries of normoxic and chronic hypoxic adult sheep, but not those from fetuses. 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 4-DAMP or 10 μM DAU 5884 for adult normoxic (A), adult hypoxic (B), and fetal normoxic (C) animals. The control response is shown with filled black circles and a solid line. The 4-DAMP response is depicted with filled black squares and a dashed line, while the DAU 5884 response is illustrated with filled gray triangles 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. Statistical significance is noted between control and 4-DAMP groups (*p < 0.05) or DAU 5884 (#p < 0.05). 4-DAMP data are based on 16 adult normoxic arteries (5 animals), 13 adult hypoxic arteries (5 animals), and 6 fetal normoxic arteries (3 animals), whereas Dau 5884 data are based on 21 adult normoxic arteries (6 animals), 8 adult hypoxic arteries (3 animals), and 13 fetal normoxic arteries (6 animals).