Terrance M Phernetton

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During the follicular phase of the ovarian cycle, when the local estrogen-to-progesterone ratio is elevated, uterine blood flow is elevated. This vasodilatory response is reproduced by exogenous 17beta-estradiol (E2beta) administration via a nitric oxide (NO)-mediated mechanism. We hypothesized that endogenous ovarian estrogen and exogenous E2beta treatment(More)
Pregnancy is characterized by elevations in uterine but not omental artery nitric oxide synthase (NOS)-specific activity. We hypothesized that increases in NO production during pregnancy are associated with elevations in protein expression of the constitutive isoform, endothelial cell NOS (ecNOS), in uterine but not systemic arteries. Arterial NOS-specific(More)
Pregnancy and the follicular phase are physiological states of elevated oestrogen levels and rises in uterine blood flow (UBF). The dramatic increase in utero-placental blood flow during gestation is required for normal fetal growth and development. Oestrogen exerts its vasodilatory effect by binding to its specific oestrogen receptors (ER) in target cells,(More)
OBJECTIVE Our purpose was to determine whether the fetal acidosis and hypoxia previously demonstrated in animal models with maternal nifedipine infusion is the result of a decrease in uteroplacental or fetoplacental blood flow and whether this effect is exacerbated by a higher drug concentration and duration of infusion. STUDY DESIGN Ten chronically(More)
Acute administration of 17beta-estradiol (E2beta) leads to increases in cardiac output, oxygen delivery, and oxygen consumption and increases the critical cardiac output in the nonpregnant sheep. We sought to determine whether the lack of a critical cardiac output or flow-dependent oxygen consumption during states of low cardiac output in late gestation can(More)
The objective of the current study was to develop an ovine animal model for consistent study of uterine blood flow (UBF) changes during synchronized ovarian cycles regardless of season. Sheep were surgically bilaterally instrumented with uterine artery blood flow transducers and 5-7 days later implanted with a vaginal progesterone (P(4))-controlled internal(More)
Prolonged 17beta-estradiol (E2beta) infusion decreases mean arterial pressure (MAP) and systemic vascular resistance (SVR) while increasing heart rate (HR) and cardiac output (CO). It is unclear, however, which systemic vascular beds show increases in perfusion. The purpose of this study was to determine which reproductive and nonreproductive vascular beds(More)
OBJECTIVE To determine the effects of maternal abdominal carbon dioxide (CO2) insufflation on placental blood flow and fetal blood gas measurements in the pregnant ewe. METHOD Five time-bred ewes at 110 days' gestation were surgically prepared with maternal and fetal catheters placed for subsequent measurement of vascular pressures, blood gas tensions,(More)
Nitric oxide (NO) production has been shown to increase uterine blood flow and be elevated in ewes carrying multiple fetuses during late gestation. Vascular endothelial growth factor (VEGF) has been reported to increase eNOS expression and NO production in endothelial cell cultures. As angiogenesis and vasodilatation of the uterine and placental vascular(More)
In late pregnancy the electrocortical activity (ECoG) in the ovine fetus starts to cycle between high and low voltage states. During the high voltage states of this activity fetal regional blood flows are decreased, and heart rate and fetal arterial blood pressure are both increased. Jensen et al. (1986) have postulated that these changes may be mediated by(More)