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

1995 ◽  
Vol 268 (2) ◽  
pp. R303-R309 ◽  
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.

Transplacental clearance and blood flows of bovine gravid uterus at several stages of gestation

1987 ◽  
Vol 253 (5) ◽  
pp. R735-R739 ◽  
Author(s):  
L. P. Reynolds ◽  
C. L. Ferrell
Keyword(s):  
Blood Flow ◽  
Statistical Model ◽  
Deuterium Oxide ◽  
Gravid Uterus ◽  
Uterine Blood Flow ◽  
Blood Flows ◽  
Bovine Placenta ◽  
Umbilical Blood ◽  
Placental Blood ◽  
Umbilical Blood Flow

Rates of uterine and umbilical blood flows and transplacental clearance of deuterium oxide (D2O) were determined for cows on 137 +/- 1.0 (SE, n = 9), 180 +/- 0.5 (n = 8), 226 +/- 0.4 (n = 9), and 250 +/- 1.8 (n = 5) days of gestation. From days 137 to 250, rates increased 4.5-fold for uterine blood flow, 21-fold for umbilical blood flow, and 14-fold for clearance of D2O. Changes in rates of umbilical blood flow and D2O clearance paralleled increased rates of fetal growth and metabolism, which have previously been reported to occur during the last half of gestation. The regressions of D2O clearance on uterine and umbilical blood flows were significant (P less than 0.01) and explained 94-99% of the variation in placental clearance of D2O. Because the rate of D2O clearance was always less than that of uterine and umbilical blood flows, and because a relatively simple statistical model explained most of the variation in clearance, it was suggested that a concurrent or countercurrent arrangement of maternal and fetal placental microvasculatures is not adequate to explain clearance of highly diffusable substances across the bovine placenta. In addition, a placental exchange diagram of the data showed the existence of severe uneven distribution of maternal and fetal placental blood flows and/or significant shunting of maternal and fetal placental flows away from areas of exchange. Taken together, these data indicate that the placenta of the cow, like those of the sheep and goat, represents a relatively inefficient system of transplacental exchange.

Metabolism of the gravid uterus, foetus and utero-placenta at several stages of gestation in cows

1986 ◽  
Vol 106 (3) ◽  
pp. 437-444 ◽  
Author(s):  
L. P. Reynolds ◽  
C. L. Ferrell ◽  
Debra A. Robertson ◽  
S. P. Ford
Keyword(s):  
Blood Flow ◽  
Deuterium Oxide ◽  
N Uptake ◽  
Gravid Uterus ◽  
Uterine Blood Flow ◽  
Indwelling Catheters ◽  
Blood Flows ◽  
Umbilical Blood ◽  
Rate Of Increase ◽  
Umbilical Blood Flow

SummaryTo quantify changes in rates of metabolism and nutrient uptake of gravid uteiine, foetal and utero-placental tissues throughout gestation, mature Hereford cows received surgery at 132 ± 0·6 (n = 12), 176 ± 0·5 (n = 8), 220 ±0·4 (n = 11) and 245 ±1·5 (n = 7) days after mating. Indwelling catheters were implanted into a uterine artery and vein of all cows. Foetal catheters also were implanted into an umbilical vein and foetal femoral artery and vein (days 176 and 220) or into a placental artery and two placental veins (days 132 and 245). Approximately 5 days after surgery, deuterium oxide was infused into a foetal femoral venous or placental venous catheter during a 3 h period to quantify uterine and umbilical blood flows by steady-state diffusion methods. Oxygen, glucose, lactate and α-amino acid nitrogen concentrations were determined for uterine and foetal blood samples collected during this procedure.Uterine blood flow increased 4·5-fold (2·92–13·181/min) and umbilical blood flow increased 21-fold (0·28–5·861–min) during the interval of gestation studied. The relative rate of increase of umbilical blood flow was about twice as great as that of uterine blood flow. Uterine arterial and umbilical venous concentrations as well as uterine arterial-venous and umbilical venous-arterial concentration differences in metabolites changed little with stage of gestation. However, because rates of blood flow increased, uptakes of O2, glucose and α-amino N by the gravid uterus and foetus increased as gestation advanced. The proportion of gravid uterine uptakes utilized by the foetus increased from day 137 to 226 for O2 (24–58%) and from day 137 to 180 for glucose (4–19%), then remained relatively constant. The proportion of gravid uterine α-amino N uptake utilized by the foetus remained relatively constant and averaged 60%. A net secretion of lactate from the utero-placenta to the uterine and foetal circulations was observed and increased as gestation advanced. These data indicate that increased rates of uptake or secretion of metabolites by tissues of the gravid uterus can be explained primarily by increased rates of uterine and umbilical blood flows.

Differential responses of uterine and umbilical vasculatures to angiotensin II and norepinephrine

1990 ◽  
Vol 259 (1) ◽  
pp. H197-H203 ◽  
Author(s):  
K. E. Clark ◽  
G. L. Irion ◽  
C. E. Mack
Keyword(s):  
Blood Flow ◽  
Angiotensin Ii ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Base Line ◽  
Ang Ii ◽  
Uterine Blood Flow ◽  
Umbilical Blood ◽  
Arterial Blood ◽  
Pregnant Sheep

Although the uterine vascular responses to endogenous vasoactive substances have been extensively investigated in pregnant sheep, the fetal umbilical responses to angiotensin II (ANG II) and norepinephrine (NE) have not been well characterized. Twenty-five pregnant ewes between 105 and 115 days of gestation were anesthetized and instrumented for hemodynamic measurements, systemic fetal and maternal intravenous infusions, and local maternal uterine arterial infusions of ANG II and NE. Fetal and maternal arterial pressure and heart rate, maternal uterine blood flow (total of left and right middle uterine arteries), and fetoplacental blood flow (common umbilical artery) were measured during continuous infusions of ANG II or NE. Fetal infusions of ANG II (0.03–1.0 micrograms.min-1.kg estimated fetal body wt-1) increased fetal arterial blood pressure by as much as 44% over base-line values, decreased umbilical blood flow by as much as 63%, and increased umbilical vascular resistance by up to 345%. Fetal infusions of NE (0.1–3 micrograms.min-1.kg-1) increased fetal arterial pressure 42% and increased umbilical vascular resistance by up to 38% but did not significantly alter fetoplacental blood flow. No significant maternal changes were observed during fetal infusions. Maternal infusion of ANG II increased maternal arterial pressure by as much as 59% and significantly increased uterine vascular resistance at the two highest doses but significantly decreased uterine blood flow only at the highest dose (17%; P less than 0.05). Maternal infusions of NE increased arterial pressure by as much as 113%, decreased uterine blood flow by as much as 76%, and increased uterine vascular resistance 3- to 10-fold over the base-line value.(ABSTRACT TRUNCATED AT 250 WORDS)

Uteroplacental blood flow during hyperthermia with and without respiratory alkalosis

1976 ◽  
Vol 41 (2) ◽  
pp. 197-201 ◽  
Author(s):  
G. K. Oakes ◽  
A. M. Walker ◽  
R. A. Ehrenkranz ◽  
R. C. Cefalo ◽  
R. A. Chez
Keyword(s):  
Blood Flow ◽  
Mean Arterial Pressure ◽  
Respiratory Alkalosis ◽  
The Other ◽  
Uterine Blood Flow ◽  
Umbilical Blood ◽  
Pregnant Sheep ◽  
Uteroplacental Blood Flow ◽  
Umbilical Blood Flow ◽  
Per Se

The effect of induced maternal hyperthermia (1.5 degrees C rise over 60 min) on the uterine and umbilical circulations was examined in two groups of chronically instrumented pregnant sheep. Hyperventilation occurred in both groups. In the group in which the resultant respiratory alkalosis was untreated (N = 5), uterine blood flow decreased to 53 +/- 3% (mean +/- SE; P less than 0.01) of control at maximal maternal temperature. Umbilical blood flow also decreased 30 +/- 6% (P less than 0.01) below control levels. In the other group, normocapnia was maintained (N = 4). Uterine blood flow decreased in this group to 75% +/- 2% (P less than 0.01) of control levels, butumbilical blood flow did not significantly change. There was no significantchange in maternal or fetal mean arterial pressure during hyperthermia ineither group. Thus, maternal hyperthermia per se results in a significant decrease in uterine blood flow primarily through an effect on uterine vascularresistance, but without a concomitant change in umbilical blood flow.

Behavioral activity during prolonged hypoxemia in fetal sheep

1988 ◽  
Vol 65 (6) ◽  
pp. 2420-2426 ◽  
Author(s):  
A. D. Bocking ◽  
R. Gagnon ◽  
K. M. Milne ◽  
S. E. White
Keyword(s):  
Blood Flow ◽  
Eye Movements ◽  
Normal Incidence ◽  
Behavioral Activity ◽  
Uterine Blood Flow ◽  
Fetal Sheep ◽  
Pregnant Sheep ◽  
Fetal Breathing ◽  
Fetal Breathing Movements ◽  
Internal Iliac

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.

Placental transfer as a function of uterine blood flow

1982 ◽  
Vol 242 (3) ◽  
pp. H429-H436 ◽  
Author(s):  
R. B. Wilkening ◽  
S. Anderson ◽  
L. Martensson ◽  
G. Meschia
Keyword(s):  
Blood Flow ◽  
Placental Transfer ◽  
Appreciable Effect ◽  
Uterine Blood Flow ◽  
Placental Perfusion ◽  
Umbilical Blood ◽  
Norepinephrine Infusion ◽  
Umbilical Blood Flow ◽  
Clearance Level ◽  
Different Levels

The effect of variations of uterine blood flow (F) on placental transfer was examined in six chronic sheep preparations by measuring the placental clearances of ethanol (CE) and antipyrine (CA) at different levels of F. Norepinephrine infusion, hemorrhage, and occlusion of the terminal aorta were used to reduce F below normal. The reduction of F had no appreciable effect on umbilical blood flow (f). In each ewe, CE significantly correlated with F. The CE vs. F relationship at constant f was curvilinear with convexity toward the clearance axis. Regression analysis showed that the equation 1/CE = 1/.911 F + 1/.831 f could account for most of the CE variance (r2 = 0.97). Implicit in this relation is the concept that, given a certain level of placental perfusion, an F/f ratio congruent to 1 is optimal for the exchange of highly diffusible inert molecules between mother and fetus [CE/(F + f) was maximum at F/f = 0.955]. CA was not significantly different from CE at low clearance level but became smaller than CE at clearance values greater than 300 ml/min. This suggests that a high rates of perfusion placental permeability was a factor in limiting CA.

Effects of hypercapnia on uterine and umbilical circulations in conscious pregnant sheep

1976 ◽  
Vol 41 (5) ◽  
pp. 727-733 ◽  
Author(s):  
A. M. Walker ◽  
G. K. Oakes ◽  
R. Ehrenkranz ◽  
M. McLaughlin ◽  
R. A. Chez
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Co2 Concentration ◽  
Arterial Pco2 ◽  
Physiological Regulation ◽  
Blood Flows ◽  
Umbilical Blood ◽  
Pregnant Sheep ◽  
Near Term ◽  
Vascular Catheters

Changes in the uterine and umbilical circulations during induced hypercapnia were studied in nine unanesthetized near-term pregnant sheep. Blood flows were measured with electromagnetic flow transducers and arterial pressures with vascular catheters implanted under anesthesia 2–16 days prior to experiments. Hypercapnia was induced in the fetus alone by giving acetazolamide iv to the fetus, 100–200 mg/kg. Mean fetal arterial Pco2 increased from49.5 to 63.4 mmHg but no significant changes in umbilical blood flowoccurred. Stepwise increases in both maternal and fetal arterial Pco2 were induced by increasing maternal inspired CO2 concentration to a maximum of 12%. Nodignificant changes occurred in uterine or umbilical circulations until hypercapnia was severe (maternal arterial Pco2 greater than 60 mmHg, fetal arterial Pco2 greater than 70 mmHg). With severe hypercapnia uterine vascular resistance increased significantly and uterine blood flow decreased despitean increase in maternal arterial pressure; fetal arterial pressure and umbilical blood flow increased significantly, but umbilical vascular resistancedid not. We conclude that hypercapnia in conscious pregnant sheep is associated with significant changes in uterine and umbilical circulations, but only when hypercapnia is severe. Carbon dioxide is unlikely to be a factor innormal physiological regulation of the uteroplacental circulation in this species.

Hepatic lactate uptake versus leg lactate output during exercise in humans

2007 ◽  
Vol 103 (4) ◽  
pp. 1227-1233 ◽  
Author(s):  
H. B. Nielsen ◽  
M. A. Febbraio ◽  
P. Ott ◽  
P. Krustrup ◽  
N. H. Secher
Keyword(s):  
Blood Flow ◽  
Glucose Uptake ◽  
Prolonged Exercise ◽  
Incremental Exercise ◽  
Hepatic Glucose Output ◽  
Arterial Lactate ◽  
Hepatic Glucose ◽  
Lactate Output ◽  
Lactate Uptake ◽  
Glucose Output

The exponential rise in blood lactate with exercise intensity may be influenced by hepatic lactate uptake. We compared muscle-derived lactate to the hepatic elimination during 2 h prolonged cycling (62 ± 4% of maximal O2 uptake, V̇o2max) followed by incremental exercise in seven healthy men. Hepatic blood flow was assessed by indocyanine green dye elimination and leg blood flow by thermodilution. During prolonged exercise, the hepatic glucose output was lower than the leg glucose uptake (3.8 ± 0.5 vs. 6.5 ± 0.6 mmol/min; mean ± SE) and at an arterial lactate of 2.0 ± 0.2 mM, the leg lactate output of 3.0 ± 1.8 mmol/min was about fourfold higher than the hepatic lactate uptake (0.7 ± 0.3 mmol/min). During incremental exercise, the hepatic glucose output was about one-third of the leg glucose uptake (2.0 ± 0.4 vs. 6.2 ± 1.3 mmol/min) and the arterial lactate reached 6.0 ± 1.1 mM because the leg lactate output of 8.9 ± 2.7 mmol/min was markedly higher than the lactate taken up by the liver (1.1 ± 0.6 mmol/min). Compared with prolonged exercise, the hepatic lactate uptake increased during incremental exercise, but the relative hepatic lactate uptake decreased to about one-tenth of the lactate released by the legs. This drop in relative hepatic lactate extraction may contribute to the increase in arterial lactate during intense exercise.

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

2004 ◽  
pp. 497-502 ◽  
Author(s):  
Danja Str??mper ◽  
Wiebke Gogarten ◽  
Marcel E. Durieux ◽  
Kristian Hartleb ◽  
Hugo Van Aken ◽  
...  
Keyword(s):  
Blood Flow ◽  
Uterine Blood Flow ◽  
Pregnant Sheep ◽  
Racemic Ketamine
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