THE INFLUENCE OF PREGNANCY ON ENDOTHELIUM-DERIVED NITRIC-OXIDE MEDIATED RELAXATIONS IN ISOLATED HUMAN RESISTANCE VESSELS

Pregnancy is associated with drastic hemodynamic adaptations, includin g a decrease in peripheral resistance. Vascular resistance is substant ially influenced by endothelium-derived nitric oxide (NO). This study was designed to investigate whether pregnancy might influence endothel ium-derived NO-mediated relaxations in human resistance arteries. Reac tivity of isolated human subcutaneous arteries, dissected out of abdom inal fat from women who underwent a laparotomy or cesarean section, wa s studied using a small vessel myograph. Addition of acetylcholine (1 nM-10 mu M) or bradykinin (1 nM-10 mu M) to precontracted preparations elicited concentration-dependent relaxation responses that were depen dent on the presence of the endothelium and were partially inhibited b y 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 inf luence on basal tone and had a similar inhibitory influence on the end othelium-mediated relaxations in vessels from non-pregnant and pregnan t women. These results indicate that the influence of endothelium-deri ved NO in human subcutaneous resistance arteries is not altered at the end of pregnancy.