Figure 2.

Contractile response of the nonpregnant equine (A) medial palmar artery and (B) vein to increasing concentrations of norepinephrine (artery, n = 10; −logEC₅₀ = 4.99 ± 0.09, in which EC₅₀ is the effective concentration of the compound required to produce 50% of the observed contractile response; vein, n = 10; −logEC₅₀ = 5.71 ± 0.06) and serotonin (artery, n = 10; −logEC₅₀ = 4.56 ± 0.59; vein, n = 10; −logEC₅₀ = 3.42 ± 1.44). Contractile response of the nonpregnant equine (C) medial palmar artery and (D) vein to increasing concentrations of lysergic acid (artery, n = 11; −logEC₅₀ was not determined; vein, n = 10; −logEC₅₀ was not determined) and ergonovine (artery, n = 9; −logEC₅₀ = 4.88 ± 0.12; vein, n = 9; −logEC₅₀ = 4.80 ± 0.10).