Rebound increase in fetal breathing movements after 24-h prostaglandin E2 infusion in fetal sheep

1996 ◽  
Vol 80 (1) ◽  
pp. 166-175 ◽  
Author(s):  
S. A. Hollingworth ◽  
S. A. Jones ◽  
S. L. Adamson
Keyword(s):  
Prostaglandin E2 ◽  
Plasma Concentrations ◽  
Treated Group ◽  
High Plasma ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Pge2 Concentration ◽  
Fetal Breathing ◽  
Fetal Breathing Movements ◽  
Rebound Increase

We investigated the hypothesis that the precipitous decrease in prostaglandin E2 (PGE2), a potent inhibitor of fetal breathing, from high plasma concentrations during labor causes a rebound stimulation of breathing without newborn concentrations falling below prelabor fetal values. Fetal plasma PGE2 concentration was gradually increased from 384 +/- 82 (SE) pg/ml in 2-h steps [0 (baseline), 1.5, 3, and 6 micrograms/min] to labor levels (1,230 +/- 381 pg/ml at 6 micrograms/min) and then was maintained for 24 h (n = 9). PGE2 at 1.5 micrograms/min significantly decreased breathing incidence [from 42 +/- 4 (baseline) to 14 +/- 4%] and breath amplitude (from 2.1 +/- 0.5 to 1.5 +/- 0.2 arbitrary units) and increased breath-to-breath interval (from 1.16 +/- 0.07 to 1.56 +/- 0.06 s). No further dose-related changes were observed. During the first 2 h after PGE2 infusion was stopped, PGE2 concentration returned to basal (352 +/- 64 pg/ml) but breathing incidence and amplitude were significantly higher (74 +/- 8% and 2.4 +/- 0.3 arbitrary units, respectively) and breath-to-breath interval was significantly lower (0.95 +/- 0.10 s) than were basal levels. Changes arose within approximately 15 min and were maintained for at least 4 h. Breathing did not change significantly in the saline-treated group (n = 7). Results suggest that the rapid decrease in plasma PGE2 concentration at birth promotes the onset of breathing.

Effects of meclofenamate on breathing movements in fetal sheep before delivery

1988 ◽  
Vol 64 (2) ◽  
pp. 759-766 ◽  
Author(s):  
L. D. Wallen ◽  
D. T. Murai ◽  
R. I. Clyman ◽  
C. H. Lee ◽  
F. E. Mauray ◽  
...  
Keyword(s):  
Low Voltage ◽  
Late Gestation ◽  
Fetal Sheep ◽  
Electrocortical Activity ◽  
Fetal Plasma ◽  
Prostaglandin Synthase ◽  
Fetal Breathing ◽  
Fetal Breathing Movements ◽  
Synthase Inhibitor ◽  
Control Infusion

There is evidence that prostaglandins (PG), specifically PGE2, participate in the regulation of fetal breathing movements (FBM). During late gestation, when FBM occur intermittently and primarily during low-voltage electrocortical activity, the concentration of PGE2 in fetal plasma ([PGE2]) is high. During the days before delivery [PGE2] increases and FBM decrease. To determine whether the increase in [PGE2] is responsible for the concurrent decrease in FBM, we infused the prostaglandin synthase inhibitor, meclofenamate (0.7 mg.kg-1.h-1), into eight fetal sheep continuously for 5-–13 days before delivery; five control fetuses received a continuous infusion of the solvent for 5–11 days before delivery. Compared with control infusion, meclofenamate caused a significant decrease in [PGE 2] until the day of delivery and a significant increase in FBM [overall and during high-voltage electrocortical activity (HVA)] until 2 days before delivery. Although there were significant correlations between [PGE2] and FBM (overall and during HVA), both groups showed similar decreases in FBM during the 2 days before delivery. We conclude that the decrease in FBM before delivery is not dependent on the concurrent increase in [PGE2].

Prostaglandin E2 decreases fetal breathing movements, but not pulmonary blood flow, in fetal sheep

1995 ◽  
Vol 78 (4) ◽  
pp. 1477-1484 ◽  
Author(s):  
R. D. Savich ◽  
F. A. Guerra ◽  
C. C. Lee ◽  
J. A. Kitterman
Keyword(s):  
Blood Flow ◽  
Pulmonary Artery ◽  
Prostaglandin E2 ◽  
Pulmonary Blood Flow ◽  
Pulmonary Hypoplasia ◽  
Left Pulmonary Artery ◽  
Fetal Sheep ◽  
Electrocortical Activity ◽  
Fetal Breathing ◽  
Fetal Breathing Movements

Fetal breathing movements are vital for normal fetal lung growth. Inhibition of these fetal breathing movements is associated with pulmonary hypoplasia. Pulmonary hypoplasia also occurs subsequent to alterations in other factors, such as a significant decrease in pulmonary blood flow. The prostaglandin system is known to have profound effects on both fetal breathing movements and on the pulmonary vascular system. We studied six late-gestation chronically instrumented fetal sheep by using an electromagnetic flow transducer around the left pulmonary artery to determine whether a decrease in fetal breathing movements, subsequent to a continuous infusion of prostaglandin E2 (PGE2), is associated with a decrease in pulmonary blood flow. A continuous PGE2 infusion of 0.88 +/- 0.11 microgram.kg-1.min-1 over 120 min led to a significant decrease in fetal breathing movements (control 40.5 +/- 3.6%, infusion 3.3 +/- 1.6%; P < 0.001). In contrast, the PGE2 infusion had no effect on mean left pulmonary artery blood flow (control 27.7 +/- 9.3 ml.min-1.kg-1, infusion 23.8 +/- 7.0 ml.min-1.kg-1. The PGE2 infusion demonstrated central effects in the percentage of time the fetus was in high-voltage electrocortical activity (control 41.9 +/- 2.5%, infusion 56.5 +/- 5.4%; P < 0.05) and in the amount of time spent in low-voltage electrocortical activity without fetal breathing movements (control 17.5 +/- 2.7%, infusion 40.2 +/- 4.8%; P < 0.05). A significant decrease in the fetal heart rate during the infusion was seen with no effect on either the systemic or pulmonary blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ethanol on immature ovine fetal breathing movements, fetal prostaglandin E2, and myometrial activity

1994 ◽  
Vol 266 (4) ◽  
pp. R1297-R1301
Author(s):  
A. D. Bocking ◽  
L. J. Carmichael ◽  
S. Abdollah ◽  
K. R. Sinervo ◽  
G. N. Smith ◽  
...  
Keyword(s):  
Blood Lactate ◽  
Blood Glucose Concentration ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Emg Activity ◽  
Fetal Blood ◽  
Fetal Plasma ◽  
Pge2 Concentration ◽  
Fetal Breathing ◽  
Fetal Breathing Movements

In the mature ovine fetus, ethanol decreases fetal breathing movements (FBM), which is temporally related to increased prostaglandin E2 (PGE2) concentration, decreases blood glucose concentration, increases blood lactate concentration, and decreases uterine electromyographic (EMG) activity. The objective of this study was to determine the effects of ethanol on these variables in the immature fetal sheep. Experiments were conducted in pregnant ewes at 85-94 days of gestation (full term 147 days) that received a 1-h maternal infusion of 1 g ethanol/kg maternal body wt (n = 9) or an equivalent volume of saline (n = 5). The maximal maternal and fetal blood ethanol concentrations for the ethanol regimen were 1.305 +/- 0.165 and 1.458 +/- 0.137 mg/ml, respectively. Maternal infusion of ethanol (or saline) did not change the incidence of FBM, fetal plasma PGE2 concentration, heart rate, blood pressure, blood gases and pH, or uterine EMG activity. Ethanol decreased (P < 0.05) fetal blood glucose concentration from 1.18 +/- 0.10 to 0.87 +/- 0.07 and 0.89 +/- 0.09 mM at 1 and 3 h, respectively, but did not alter blood lactate concentration compared with saline infusion. These data support the hypothesis that the effects of ethanol on FBM, fetal plasma PGE2 and blood lactate concentrations, and uterine EMG activity are gestational age dependent.

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.

scholarly journals Coordinated changes in hepatic amino acid metabolism and endocrine signals support hepatic glucose production during fetal hypoglycemia

2015 ◽  
Vol 308 (4) ◽  
pp. E306-E314 ◽  
Author(s):  
Satya S. Houin ◽  
Paul J. Rozance ◽  
Laura D. Brown ◽  
William W. Hay ◽  
Randall B. Wilkening ◽  
...  
Keyword(s):  
Fetal Liver ◽  
Hepatic Glucose Production ◽  
Plasma Concentrations ◽  
Glucose Production ◽  
Late Gestation ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Hepatic Glucose ◽  
Molar Percent ◽  
Glucose Output

Reduced fetal glucose supply, induced experimentally or as a result of placental insufficiency, produces an early activation of fetal glucose production. The mechanisms and substrates used to fuel this increased glucose production rate remain unknown. We hypothesized that in response to hypoglycemia, induced experimentally with maternal insulin infusion, the fetal liver would increase uptake of lactate and amino acids (AA), which would combine with hormonal signals to support hepatic glucose production. To test this hypothesis, metabolic studies were done in six late gestation fetal sheep to measure hepatic glucose and substrate flux before (basal) and after [days (d)1 and 4] the start of hypoglycemia. Maternal and fetal glucose concentrations decreased by 50% on d1 and d4 ( P < 0.05). The liver transitioned from net glucose uptake (basal, 5.1 ± 1.5 μmol/min) to output by d4 (2.8 ± 1.4 μmol/min; P < 0.05 vs. basal). The [U-13C]glucose tracer molar percent excess ratio across the liver decreased over the same period (basal: 0.98 ± 0.01, vs. d4: 0.89 ± 0.01, P < 0.05). Total hepatic AA uptake, but not lactate or pyruvate uptake, increased by threefold on d1 ( P < 0.05) and remained elevated throughout the study. This AA uptake was driven largely by decreased glutamate output and increased glycine uptake. Fetal plasma concentrations of insulin were 50% lower, while cortisol and glucagon concentrations increased 56 and 86% during hypoglycemia ( P < 0.05 for basal vs. d4). Thus increased hepatic AA uptake, rather than pyruvate or lactate uptake, and decreased fetal plasma insulin and increased cortisol and glucagon concentrations occur simultaneously with increased fetal hepatic glucose output in response to fetal hypoglycemia.

Effect of alteration of maternal plasma progesterone concentrations on fetal behavioural state during late gestation

1997 ◽  
Vol 152 (3) ◽  
pp. 379-386 ◽  
Author(s):  
M B Nicol ◽  
J J Hirst ◽  
D Walker ◽  
G D Thorburn
Keyword(s):  
Plasma Concentrations ◽  
Maternal Plasma ◽  
Late Gestation ◽  
Emg Activity ◽  
Fetal Sheep ◽  
Plasma Progesterone ◽  
Fetal Plasma ◽  
Progesterone Synthesis ◽  
Progesterone Metabolites ◽  
Vascular Catheters

Placental progesterone synthesis exposes the fetus to high levels of progesterone and progesterone metabolites during late gestation which may influence fetal behaviour. To determine the role of maternal progesterone synthesis in the control of fetal arousal state and fetal breathing movements (FBM), the effect of raising and lowering maternal progesterone concentrations was examined in chronically catheterised fetal sheep. Fetal and maternal vascular catheters, fetal tracheal and amniotic fluid catheters as well as electrodes for recording fetal electrocortical (ECoG), electro-ocular (EOG) and nuchal muscle electromyographic (EMG) activity were implanted between 118 and 122 days gestational age (GA). Progesterone, 100 mg, administered twice daily i.m. for 3 days (130–133 days GA) resulted in a marked elevation in maternal plasma progesterone concentrations (370 ± 121%, n=5, P<0·05), but had no effect on fetal plasma concentrations. Fetal EOG episodes and the duration of fetal behavioural arousal were significantly suppressed throughout the progesterone treatment period (74·4–81·1% and 58–65% respectively, P<0·05, n=5). Four ewes received Trilostane (25 mg i.v.), a 3β-hydroxysteroid dehydrogenase inhibitor, between 136 and 140 days GA. Maternal and fetal progesterone concentrations were significantly lowered by 60 min after treatment (19·8 ± 8·0% and 39·5 ± 24·3% respectively, P<0·05). The incidence of fetal EOG activity increased from a pretreatment level of 26·8 ± 1·5 min/h to 30·3 ± 2·8 min/h at 1–6 h and to 35·0 ± 1·7 min/h (P<0·05) during the 7–12 h after Trilostane treatment. The duration of FBM episodes was significantly higher at 1–6 h and 7–12 h after Trilostane treatment (19·5 ± 3·0 and 23·6 ± 5·5 min/h respectively, P<0·05) compared with pretreatment levels (11·2 ± 1·2 min/h). We conclude that increasing maternal progesterone levels suppresses fetal EOG activity and behavioural arousal, whereas reducing maternal progesterone synthesis leads to an elevation of EOG activity and FBM. Journal of Endocrinology (1997) 152, 379–386

scholarly journals Renin dynamics in adipose tissue: adipose tissue control of local renin concentrations

2009 ◽  
Vol 296 (2) ◽  
pp. E343-E350 ◽  
Author(s):  
Jason D. Fowler ◽  
Stacy B. Krueth ◽  
David A. Bernlohr ◽  
Stephen A. Katz
Keyword(s):  
Adipose Tissue ◽  
Cardiac Tissue ◽  
Plasma Concentrations ◽  
Renin Angiotensin System ◽  
Plasma Renin ◽  
Treated Group ◽  
Rat Plasma ◽  
High Plasma ◽  
Tissue Growth

The renin-angiotensin system (RAS) has been implicated in a variety of adipose tissue functions, including tissue growth, differentiation, metabolism, and inflammation. Although expression of all components necessary for a locally derived adipose tissue RAS has been demonstrated within adipose tissue, independence of local adipose RAS component concentrations from corresponding plasma RAS fluctuations has not been addressed. To analyze this, we varied in vivo rat plasma concentrations of two RAS components, renin and angiotensinogen (AGT), to determine the influence of their plasma concentrations on adipose and cardiac tissue levels in both perfused (plasma removed) and nonperfused samples. Variation of plasma RAS components was accomplished by four treatment groups: normal, DOCA salt, bilateral nephrectomy, and losartan. Adipose and cardiac tissue AGT concentrations correlated positively with plasma values. Perfusion of adipose tissue decreased AGT concentrations by 11.1%, indicating that adipose tissue AGT was in equilibrium with plasma. Cardiac tissue renin levels positively correlated with plasma renin concentration for all treatments. In contrast, adipose tissue renin levels did not correlate with plasma renin, with the exception of extremely high plasma renin concentrations achieved in the losartan-treated group. These results suggest that adipose tissue may control its own local renin concentration independently of plasma renin as a potential mechanism for maintaining a functional local adipose RAS.

Hormonal and biophysical responses to acute hypoxemia in fetal sheep at 0.7–0.8 gestation

1990 ◽  
Vol 68 (12) ◽  
pp. 1527-1532 ◽  
Author(s):  
Kozo Akagi ◽  
John R. G. Challis
Keyword(s):  
Eye Movements ◽  
Arginine Vasopressin ◽  
Adrenocorticotropic Hormone ◽  
Minimal Change ◽  
Fetal Sheep ◽  
Fetal Breathing ◽  
Fetal Breathing Movements ◽  
Biophysical Changes

We examined whether there was a minimal change in fetal arterial [Formula: see text] necessary to elicit alterations in plasma adrenocorticotropic hormone, arginine vasopressin, or cortisol or to affect the incidence of breathing movements or eye movements in fetal sheep at 106–117 days of gestation. Fetal sheep were exposed to two levels of hypoxemia, mild (4.1 mmHg [Formula: see text] drop) (1 mmHg = 133.32 Pa) and moderate (8.4 mmHg [Formula: see text] drop), for 1 h without acidemia. Hypoxemia was induced by altering the inspired percent oxygen of the mother. No significant hormonal and biophysical changes were observed in mild hypoxemia. In moderate hypoxemia, there were significant increases of fetal adrenocorticotropic hormone and arginine vasopressin and decreased incidence of fetal breathing movements. However, there were no significant changes in cortisol or eye movements. We conclude that a fetal arterial [Formula: see text] drop of between 4.1 and 8.4 mmHg is necessary to elicit responses to hypoxemia in fetal sheep at 106–117 days of gestation in adrenocorticotropic hormone, arginine vasopressin, and fetal breathing movements, but this degree of hypoxemia does not cause changes in cortisol or fetal eye movements.Key words: fetal sheep, hypoxemia, adrenocorticotropic hormone, arginine vasopressin, cortisol, fetal breathing movements, fetal eye movements.

scholarly journals Proopiomelanocortin Processing in the Anterior Pituitary of the Ovine Fetus after Lesion of the Hypothalamic Paraventricular Nucleus

Endocrinology ◽  
2005 ◽  
Vol 146 (6) ◽  
pp. 2665-2673 ◽  
Author(s):  
M. Elizabeth Bell ◽  
Thomas J. McDonald ◽  
Dean A. Myers
Keyword(s):  
Paraventricular Nucleus ◽  
Anterior Pituitary ◽  
Limit Of Detection ◽  
Plasma Concentrations ◽  
Hybridization Signal ◽  
Mrna Levels ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Ovine Fetus ◽  
Fetal Organs

Abstract The hypothalamic-pituitary-adrenocortical axis plays an essential role in the maturation of fetal organs and, in sheep, birth. Lesioning the paraventricular nucleus (PVN) in fetal sheep prevents adrenocortical maturation and parturition without altering plasma immunoreactive ACTH concentrations. The purpose of this study was to determine the effect of PVN lesion on anterior pituitary processing of proopiomelanocortin (POMC) to ACTH, plasma concentrations of ACTH and ACTH precursors (POMC; 22-kDa proACTH), and expression of subtilisin-like prohormone convertase 3 (SPC3) in corticotropes in fetal sheep. PVN lesion did not affect anterior pituitary POMC and 22-kDa proACTH levels, whereas ACTH was significantly affected. The ACTH precursor (POMC plus 22-kDa proACTH) to ACTH ratio in the anterior pituitary was significantly increased after PVN lesion. Post-PVN lesion, fetal plasma ACTH1–39, was below the limit of detection, whereas ACTH precursors (POMC plus 22-kDa proACTH) were not affected. In the inferior region of the anterior pituitary, 40–50% of corticotropes had detectable SPC3 hybridization signal, and PVN lesion did not change the extent of colocalization of POMC and SPC3, or SPC3 mRNA levels within corticotropes. Neither the percent of corticotropes in the superior region containing SPC3 hybridization (7–12%) or hybridization signal strength was altered in response to PVN lesion. In conclusion, the fetal PVN is necessary for sustaining adequate anterior pituitary processing of POMC to ACTH and ACTH release needed for maturing the adrenal cortex in the sheep fetus.

Effects of intracisternal monoamines on breathing movements in fetal sheep

1993 ◽  
Vol 264 (6) ◽  
pp. R1139-R1149
Author(s):  
S. A. Joseph ◽  
D. W. Walker
Keyword(s):  
Cerebrospinal Fluid ◽  
High Voltage ◽  
Large Amplitude ◽  
Rapid Onset ◽  
In Utero ◽  
Fetal Sheep ◽  
Fetal Breathing ◽  
Fetal Breathing Movements ◽  
Intracisternal Injection

The effects of intracisternal administration of tyramine on fetal breathing movements (FBM), electrocortical (ECoG) and nuchal muscle activities, and cerebrospinal fluid (CSF) monoamine concentrations have been studied in unanesthetized fetal sheep (124-140 days gestation) in utero. In 18 trials (8 fetuses) infusion of 50 or 100 micrograms/kg tyramine increased the incidence of FBM from 32.2 +/- 2.0 to 79.4 +/- 4.7%/h (P < 0.05) and increased mean breath amplitude from 6.4 +/- 0.4 to 11.8 +/- 1.6 mmHg (P < 0.05). FBM incidence during high-voltage ECoG activity increased from 3.3 +/- 0.6 to 22.5 +/- 3.6%/h (P < 0.05). Tyramine infusion (100 micrograms/kg) significantly increased (P < 0.05) the CSF concentrations of dopamine from 129.5 +/- 26.2 to 10,222.4 +/- 1,103.6 pg/ml, of norepinephrine from 74.7 +/- 11.0 to 2,238.6 +/- 143.5 pg/ml, and of serotonin from 1,824.5 +/- 340.7 to 3,888.7 +/- 1,335.2 pg/ml. Intracisternal injection of dopamine or norepinephrine (10-20 micrograms) caused the rapid onset of large-amplitude FBM, which often continued throughout high-voltage ECoG activity. In contrast, serotonin (20-40 micrograms) caused cessation of FBM and change of the ECoG from low- to high-voltage activity. These results indicate that neuronal release of catecholamines in the CNS has excitatory effects on FBM.

Sign in / Sign up

Export Citation Format

Share Document