Lorca RA, et al. - During pregnancy, chronic hypoxia seen with living in high altitudes (HA) attenuates uterine artery blood flow, so researchers investigated if reduced vasodilation of myometrial arteries (MAs) was partly responsible for this lesser pregnancy blood flow. This study included healthy residents of high (2902±39 m) or low altitudes (LA; 1669±10 m), in whom the MA vasoreactivity was evaluated. They noted a reduction in both acetylcholine and bradykinin vasodilation by 56% and 33%, respectively, by the NO synthase inhibitor L-N^G-nitroarginine methyl ester at LA. Based on the findings, a possible contribution of reduced NO-dependent MA vasodilation to diminished uteroplacental perfusion in HA pregnancies was suggested.