Effects of hyperthermia on fetal and maternal plasma prostaglandin concentrations and uterine activity in sheep

Andrianakis, P.; Walker, David W.; Ralph, M. M.; Thorburn, G. D.

doi:10.1016/0090-6980(89)90148-2

Cited by 14 publications

(11 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Surgery was performed at 121-125 days gestation under general anaesthesia (1-2% halothane; 50:50v/v nitrous oxide:oxygen) using aseptic surgical procedures, as described previously (Andrianakis et al 1989;Walker et al 1990). The uterus was exposed through a mid-line laparotomy and incised to allow a fetal hindlimb to be withdrawn.…”

Section: Methodsmentioning

confidence: 99%

“…The temperature of the fetal sheep is approximately 0 5°C higher than that of the mother (Oakes, Ehrenkranz, Walker, Cefalo & Chez, 1976;Lotgering, Gilbert & Longo, 1983;Bell, 1987; Andrianakis, Walker, Ralph & Thorburn, 1989;Laburn, Mitchell & Goelst, 1992). It has been estimated that, of the heat generated by metabolic processes in the fetoplacental unit, 86% is lost to the mother across the placenta and 14% passes through fetal skin into the amniotic fluid (Gilbert, Schroder, Kawamura, Dale & Power, 1985).…”

Section: Introductionmentioning

confidence: 99%

“…Heat stress during pregnancy is also associated with increased fetal plasma concentrations of prostaglandins and prolactin (Andrianakis et al 1989;Walker, Davies & McMillen, 1990) and, when prolonged, hyperthermia results in retardation of fetal growth (Alexander & Williams, 1971;Bell, 1987), microencephaly and cerebral lesions (Upfold, Smith & Edwards, 1987). If heat stress resulted in a decrease of blood flow to some fetal organs, then alterations of tissue substrate supply, tissue growth, and angiogenesis might result if this situation were frequent or prolonged.…”

Section: Introductionmentioning

confidence: 99%

“…In species such as sheep, heat stress is accompanied by hyperventilation so that both maternal and fetal blood Pco, are lowered markedly (Hales, Hopkins & Thorburn, 1972;Oakes et al 1976; Walker & Davies, 1986;Andrianakis et al 1989). Whilst it is known that fetal cerebral blood flow is increased under hypercapnic conditions (Jones, Sheldon, Peeters, Makowski & Meschia, 1978), the effect of hypocapnia is not known.…”

Section: Introductionmentioning

confidence: 99%

“…The fetus must cope with increases of intra-uterine temperature due to maternal fever, maternal exercise, or exposure to high environmental temperatures (Lotgering et al 1983;Bell, 1987;Andrianakis et al 1989;Laburn et al 1992). In species such as sheep, heat stress is accompanied by hyperventilation so that both maternal and fetal blood Pco, are lowered markedly (Hales, Hopkins & Thorburn, 1972;Oakes et al 1976; Walker & Davies, 1986;Andrianakis et al 1989).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Cardiovascular responses to heat stress in late gestation fetal sheep

Dw¹,

Hale²,

Aa³

et al. 1995

Experimental Physiology

View full text Add to dashboard Cite

SUMMARYHeat stress during pregnancy in sheep is associated with respiratory alkalosis in both the mother and fetus, and, if prolonged, fetal growth is retarded. In seven pregnant sheep at 130-137 days gestation we used 15 ,um diameter radioactive microspheres to determine the effect of raising the environmental temperature from 20 to 43°C for 8 h on uteroplacental blood flows and the distribution of cardiac output in the ewe and fetus. Fetal cardiac output increased slightly from 47.0 + 3.2 (mean + S.E.M.) to 54.0 + 3-6 ml min-' (100 g tissue)-', fetal arterial pressure and heart rate were unchanged, and total vascular conductance in the fetus increased significantly from 12397 + 1111 to 14732 + 1569 ml min-kg-mmHg-' (P <0.01). Tissue blood flows (in ml min-' (100 g)-1) increased significantly (P < 0.05) in the fetal body (e.g. nasal mucosa, torso and foreleg skin, adrenal, thyroid and thymus glands, brown and omental fats, heart, urinary bladder and carcass) and the fetal brain (e.g. cerebellum, cerebral grey matter, cervical spinal cord and pituitary gland). These regional vasodilatations occurred despite a significant fall (P < 0-01) in fetal arterial 02 saturation (55.2 + 1-8 vs. 38-6 ± 2.4 %), Po2 (18.1 + 0-7 vs. 13.5 + 0.8 mmHg) and PCO2 (51.0 + 1-8 vs. 36-1 + 2-3 mmHg); under normothermic conditions hypoxia is associated with peripheral vasoconstriction. Because hypocapnia would also be expected to cause cerebral vasoconstriction it is suggested that during hyperthermia, hypoxia-and hypocapnia-induced vasoconstrictions are reduced by the release of vasodilator substances, or a decrease of sympathoadrenal effector responses. Blood flow to the fetal and maternal sides of the placenta did not change during the heat stress, suggesting that perfusion-dependent transfer of heat from fetus to mother across the placenta does not increase under hyperthermic conditions.

show abstract

Section: Methodsmentioning

confidence: 99%