Figure 5.

Constriction and relaxation responses of mesenteric arteries from advanced maternal age nulliparous or postpartum rats at 3 months postpartum, or equivalent age in never pregnant (virgin) controls (~13.5 months old). (A) Constriction to phenylephrine (PE, n = 5–11) and (B) relaxation to methylcholine (MCh, n = 4–13) were unaltered by maternal group. Inset shows one-way ANOVA analysis of area under curve (AUC) summary data. (C) Sensitivity to MCh was reduced in mesenteric arteries following inhibition of nitric oxide synthase (L-NAME). (D) Analysis of pEC₅₀ summary data showed that L-NAME significantly reduced sensitivity to MCh-induced relaxation from virgin and postpartum, but not nulliparous, rats. The effect of parity and L-NAME on vasodilation to MCh (pEC₅₀) were analyzed by two-way ANOVA: drug effect p < 0.01, with Sidak's post-test, ^*p < 0.05.