Fig. 3.
Concentration-dependent effects of adrenergic agonists in extraembryonic arteries (allantoic and yolk sac) from 19-day chicken embryos. Contractile effects of the nonselective adrenergic receptor agonist norepinephrine (NE, a), the α1-adrenergic agonist phenylephrine (b), the α2-adrenergic agonist oxymetazoline (c), and the β-adrenergic agonist isoproterenol (d). For the isoproterenol experiments, vessels were pre-contracted with KCl (62.5 mM). Data points are presented as mean ± SE. *, **, ***p < 0.05, 0.01, 0.001 for difference (yolk sac vs. allantoic) in E max or at the individual value (in panel c) because E max was not reached