LAUSR

Abstract Increasing ovine placentome blood perfusion improves placental efficiency while increasing the likelihood of healthier birth weights and lower mortality rates in offspring. Invasive surgical techniques have been used to examine uteroplacental blood flow; however, non-invasive Doppler ultrasonography has recently been observed as a reliable alternative method. Even so, smaller tissues, such as placentomes, do not permit reliable measurements of vessel diameter and subsequently blood flow calculations. Objectives were to validate Doppler ultrasonography techniques for examining placentome blood perfusion in ewes administered vasoactive compounds. Ewes (n = 28) were bred to a single ram, with pregnancy being confirmed prior to experimentation. For experiment 1, placentome blood perfusion was determined pre-infusion (PRE1; n = 8) and 3–5 minutes post i.v. infusion with sodium nitroprusside at 5 μg/kg of body weight (SN5; n = 4) or 10 ug/kg of body weight (SN10; n = 4). Immediately after ultrasonography all ewes were administered N(G)-Nitro- l -arginine methyl ester (L-NAME) at 12.5 mg/kg of body weight (n = 8) and imaged for placentome perfusion 30 min post i.v. infusion. For experiment 2, ewes (n = 15) were first imaged for placentome perfusion prior to the administration of antioxidants (min 0; PRE2) and then 30 min following i.v. infusion of melatonin (MEL; 100 ug/kg of body weight), ascorbate (ASC; 10 mg/kg of body weight), or vehicle (VEH; 50% ethanol solution). Data for experiment 1 and 2 were analyzed separately by ANOVA with least significant difference test. For experiment 1, the percent area of placentome perfusion was not different (P > 0.05) between SNP and l -NAME infusions. However, the summation and average integrated pixel density of placentomes were increased (P  l -NAME. For experiment 2, the percent area of placentome perfusion was increased (P