A and B, Uterine arteries from high-altitude pregnant sheep were transfected with 100 nmol/L miR-210-LNA or negative control (Neg Ctr) under 10.5% O2 for 48 hours and STOC frequency and amplitude were measured after the treatment. Data are means ± SEM of 5 animals in each group. *P < 0.05, miR-210-LNA versus Neg Ctr. C - F, Uterine arteries from high-altitude nonpregnant sheep were transfected with Neg Ctr (C, D) or 100 nmol/L miR-210-LNA (E, F) under 10.5% O2 for 48 hours, in the presence of vehicle control (Ctr) or 17β-estradiol (E2β 0.3 nmol/L)/progesterone (P4; 100.0 nmol/L). STOC frequency and amplitude were measured after the treatment. Data are means ± SEM of 5 animals in each group; repeated measures ANOVA with the post hoc Bonferroni/Dunn test; *P < 0.05, E2β/P4 versus Ctr.