The Effects of S(+)-Ketamine and Racemic Ketamine on Uterine Blood Flow in Chronically Instrumented Pregnant Sheep

Experiments were conducted in unanesthetized, chronically catheterized pregnant sheep to determine the fetal behavioral response to prolonged hypoxemia produced by restricting uterine blood flow. Uterine blood flow was reduced by adjusting a vascular occluder placed around the maternal common internal iliac artery to decrease fetal arterial O2 content from 6.1 +/- 0.3 to 4.1 +/- 0.3 ml/dl for 48 h. Associated with the decrease in fetal O2 content, there was a slight increase in fetal arterial PCO2 and decrease in pH, which were both transient. There was an initial inhibition of both fetal breathing movements and eye movements but no change in the pattern of electrocortical activity. After this initial inhibition there was a return to normal incidence of both fetal breathing movements and eye movements by 16 h of the prolonged hypoxemia. These studies indicate that the chronically catheterized sheep fetus is able to adapt behaviorally to a prolonged decrease in arterial O2 content secondary to the restriction of uterine blood flow.

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Effects of hyperthermia on uterine blood flow and shunting through uterine arteriovenous anastomoses in the late-pregnant ewe

Reproduction Fertility and Development ◽

10.1071/rd99034 ◽

1999 ◽

Vol 11 (5) ◽

pp. 201 ◽

Cited By ~ 1

Author(s):

Suzanne L. Miller ◽

Graham Jenkin ◽

David W. Walker

Keyword(s):

Blood Flow ◽

Experimental Period ◽

Respiratory Alkalosis ◽

Uterine Horn ◽

Arteriovenous Anastomoses ◽

Uterine Blood Flow ◽

Ambient Conditions ◽

Total Blood ◽

Uterine Arteries ◽

Pregnant Sheep

The effect of maternal hyperthermia on uterine blood flow (UBF) through the two main uterine arteries and on the proportion of UBF shunted through uterine arteriovenous anastomoses (AVAs) was investigated. Eight late-pregnant ewes were exposed to normothermic (22–23˚C) or hyperthermic (approx-imately 39˚C) ambient conditions for 8 h. UBF was measured in the left and right uterine arteries using flow probes and microspheres were injected into the uterine artery before, during and after the experimental period. The distribution of microspheres between the uterus and lungs was determined to calculate changes in capillary and AVA blood flows. Hyperthermia produced a significant (P<0.05) increase in maternal core temperature (+1.5˚C), increase in maternal blood pH (+0.21; P<0.05) and decrease in maternal pCO 2 (–16.2 mmHg; P<0.05). Blood flow to the uterine horn ipsilateral to the corpus luteum (CL) remained unchanged during hyperthermia, whereas total UBF and blood flow to the contralateral uterine horn were significantly decreased (P<0.05), by 23.1% and 20.8%, respectively, of pre-heat control values. The proportion of UBF shunted through uterine AVAs during hyperthermia was not significantly different from values observed in normothermic ewes (21.9 0.7%). Mild to moderate hyperthermia in late-pregnant sheep induces respiratory alkalosis and decreases total blood flow to the uterus, brought about by a decrease in blood flow to the uterine horn contralateral, but not ipsilateral to the CL. Heat treatment does not alter the proportion of UBF traversing uterine AVAs.

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Oxygen, glucose, and lactate uptake by fetus and placenta during prolonged hypoxemia

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1995.268.2.r303 ◽

1995 ◽

Vol 268 (2) ◽

pp. R303-R309 ◽

Cited By ~ 5

Author(s):

S. B. Hooper ◽

D. W. Walker ◽

R. Harding

Keyword(s):

Blood Flow ◽

Glucose Uptake ◽

Lactate Clearance ◽

Gravid Uterus ◽

Uterine Blood Flow ◽

Fetal Circulation ◽

Umbilical Blood ◽

Pregnant Sheep ◽

Lactate Uptake ◽

Arterial O2 Saturation

Our aim was to compare the effects of short (4 h) and prolonged (24 h) periods of reduced uterine blood flow (RUBF) on fetal and placental uptake of O2, glucose, and lactate. In pregnant sheep, uterine and umbilical blood flows were measured under normal conditions and after 4 and 24 h of RUBF. A 50% reduction in uterine blood flow caused a 56% reduction in fetal arterial O2 saturation (SaO2). Umbilical blood flow increased from 325 +/- 33 to 378 +/- 32 ml.min-1.kg-1 (P < 0.05) after 4 h but was not different from pre-RUBF values after 24 h. O2 uptake by the gravid uterus was not altered by RUBF, due to an increase (84%) in uterine O2 extraction. Similarly, uteroplacental and fetal O2 consumptions and fetal glucose uptake were not affected by RUBF, whereas uteroplacental glucose uptake was significantly reduced after 4 h (by 42%) and 24 h (by 58%) of RUBF. Fetal lactate uptake was greatly reduced from 78.7 +/- 15.5 to -167 +/- 57 mumol.min-1.kg-1 after 4 h and to -198 +/- 80 mumol.min-1.kg-1 after 24 h of RUBF; negative values indicate placental lactate uptake from the fetal circulation. Thus, although RUBF significantly reduced fetal SaO2, fetal and uteroplacental O2 consumptions did not change. In addition, although fetal glucose uptake was not altered by RUBF, during RUBF the placenta became a major site of lactate clearance from the fetal circulation.

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Uterine blood flow responses to ICI 182 780 in ovariectomized oestradiol-17β-treated, intact follicular and pregnant sheep

The Journal of Physiology ◽

10.1113/jphysiol.2005.086439 ◽

2005 ◽

Vol 565 (1) ◽

pp. 71-83 ◽

Cited By ~ 54

Author(s):

Ronald R. Magness ◽

Terrance M. Phernetton ◽

Tiffini C. Gibson ◽

Dong-bao Chen

Keyword(s):

Blood Flow ◽

Uterine Blood Flow ◽

Pregnant Sheep

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Distribution of uterine blood flow in the pregnant sheep

American Journal of Obstetrics and Gynecology ◽

10.1016/0002-9378(68)90074-4 ◽

1968 ◽

Vol 101 (3) ◽

pp. 409-412 ◽

Cited By ~ 75

Author(s):

E.L. Makowski ◽

G. Meschia ◽

W. Droegemueller ◽

F.C. Battaglia

Keyword(s):

Blood Flow ◽

Uterine Blood Flow ◽

Pregnant Sheep

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Effects of Cafedrine/Theodrenaline, Etilefrine and Ephedrine on Uterine Blood Flow during Epidural-Induced Hypotension in Pregnant Sheep

Fetal Diagnosis and Therapy ◽

10.1159/000086816 ◽

2005 ◽

Vol 20 (5) ◽

pp. 377-382 ◽

Cited By ~ 7

Author(s):

D. Strümper ◽

W. Gogarten ◽

M.E. Durieux ◽

K. Hartleb ◽

H. van Aken ◽

...

Keyword(s):

Blood Flow ◽

Uterine Blood Flow ◽

Induced Hypotension ◽

Pregnant Sheep

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Effect of prostaglandin E2 on ovine maternal placental blood flow

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1976.231.3.754 ◽

1976 ◽

Vol 231 (3) ◽

pp. 754-759 ◽

Cited By ~ 34

Author(s):

JH Rankin ◽

TM Phernetton

Keyword(s):

Blood Flow ◽

Renal Blood Flow ◽

Placental Transfer ◽

Venous Catheter ◽

Uterine Blood Flow ◽

Blood Flows ◽

Pregnant Sheep ◽

Maternal Brain ◽

Regional Blood Flows ◽

Near Term

The effect of PGE2 on regional blood flows in the chronically catheterized near-term pregnant sheep was investigated using radioactive microspheres. The injection of 20 mug PGE2 per kilogram into the left ventricle of eight sheep resulted in no change in maternal brain and noncotyledonary uterine flow. The renal blood flow increased from 692 to 892 ml/min (P less than 0.004). The uterine blood flow decreased from 673 to 317 ml/min (P less than 0.001). The trium was bypassed by injecting 7 mug PGE2 per kilogram of sheep into a fetal venous catheter and permitting it to reach the placental vasculature after placental transfer. Eleven sets of observations were made in eight animals. We observed no change in the intrauterine pressure, maternal brain flow, and noncotyledonary uterine blood flow secondary to this procedure. The maternal renal blood flow changed from 592 to 669 ml/min (P less than 0.007). The uterine blood flow increased from 762 to 853 ml/min (P less than 0.02). The uterine vascular resistance decreased from 0.124 to 0.115 mmHg x min/ml (P less than 0.04). It was concluded that 1) PGE3 crosses the placenta quite readily, and 2) PGE3 causes dilatation of the maternal placental vascular bed.

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The Effect of Local Anaesthetics on Uterine Blood Flow and Oxygen Consumption in Non-Pregnant Sheep

Survey of Anesthesiology ◽

10.1097/00132586-197912000-00040 ◽

1979 ◽

Vol 23 (6) ◽

pp. 377

Author(s):

E. LANZ ◽

H. SCHLERETH

Keyword(s):

Blood Flow ◽

Oxygen Consumption ◽

Local Anaesthetics ◽

Uterine Blood Flow ◽

Pregnant Sheep

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Measurement of Uterine Blood Flow and Uterine Metabolism

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1958.195.3.614 ◽

1958 ◽

Vol 195 (3) ◽

pp. 614-620 ◽

Cited By ~ 42

Author(s):

N. S. Assali ◽

K. Dasgupta ◽

A. Kolin ◽

L. Holms

Keyword(s):

Blood Flow ◽

Uterine Contraction ◽

Uterine Blood Flow ◽

Progressive Decrease ◽

Flow Meter ◽

Induced Labor ◽

Uterine Contractions ◽

Uterine Involution ◽

Pregnant Sheep

Uterine blood flow has been measured with a chronically implanted miniature electromegnetic flow meter in unanesthetized pregnant sheep and dogs during spontaneous and oxytocin induced labor and followed in the same animal for several postpartum days. In either spontaneous or oxytocin induced labor, uterine contractions are accompanied by a significant decrease in uterine blood flow and relaxations by the return of the flow to or higher than control values. The decrease is roughly proportional to the intensity of uterine contraction. When the contraction is of a tetanic nature and not followed by relaxation, uterine ischemia is so severe that the fetus might succumb. After the delivery of the fetus and before the expulsion of the placenta, uterine blood flow falls slightly. However, after separation and expulsion of the placenta, uterine blood flow falls precipitously. Thereafter, a very slight and progressive decrease continues for several days paralleling uterine involution.

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