The influence of pregnancy on endothelium‐derived nitric oxide mediated relaxations in isolated human resistance vessels

Pregnancy is associated with drastic hemodynamic adaptations, including a decrease in peripheral resistance. Vascular resistance is substantially influenced by endothelium-derived nitric oxide (NO). This study was designed to investigate whether pregnancy might influence endothelium-derived NO-mediated relaxations in human resistance arteries. Reactivity of isolated human subcutaneous arteries, dissected out of abdominal fat from women who underwent a laparotomy or cesarean section, was studied using a small vessel myograph. Addition of acetylcholine (1 nM-10 microM) or bradykinin (1 nM-10 microM) to precontracted preparations elicited concentration-dependent relaxation responses that were dependent on the presence of the endothelium and were partially inhibited by the NO-synthase inhibitor nitro-L-arginine (0.1 mM). The relaxations to acetylcholine and bradykinin were similar in vessels isolated from pregnant and non-pregnant women. Nitro-L-arginine (0.1 mM) had no influence on basal tone and had a similar inhibitory influence on the endothelium-mediated relaxations in vessels from non-pregnant and pregnant women. These results indicate that the influence of endothelium-derived NO in human subcutaneous resistance arteries is not altered at the end of pregnancy.