Fluid production by <i>in vitro</i> lungs from fetal guinea pigs

Perks, A. M.; Doré, Jules J.E.; Dyer, R. M.; Thom, J.; Jc, Marshall; Ruiz, Teresa; Woods, B A; Vanderhorst, E.; Ziabakhsh, Sepideh

doi:10.1139/y90-072

Cited by 26 publications

(19 citation statements)

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“…The basis of the method and confirmation of its validity have been given previously; simultaneous use of the Dextran with 125 I-labelled albumin tracer showed close agreement in rates, but the dye gave less scatter around the lines of best fit (see below) (Cassin & Perks, 1982;Perks et al 1990). Pregnant guinea-pigs were anaesthetized with halothane (Fluothane; Ayers, Montreal, Qu ebec, Canada) until full inhibition of the corneal reflex; final death was produced by severing the carotid arteries.…”

Section: Methodsmentioning

confidence: 60%

“…The rates of fluid production were calculated from the fall in concentration of Blue Dextran, as described previously (Cassin & Perks, 1982;Perks et al 1990). Rates were estimated from plots of the total volume of fluid against time, with readings recorded every 10 min; the total volume of fluid was the sum of that within the lungs and that removed for study.…”

Section: Quantification Of Results and Statistical Methodsmentioning

confidence: 99%

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The effect of dopamine on lung liquid production by in vitro lungs from fetal guinea‐pigs

Chua

Perks

1998

The Journal of Physiology

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During gestation, fetal lungs produce large quantities of fluid which contribute substantially to the amniotic fluid, particularly in the guinea-pig, where production rates appear to be higher than those for urine (Strang, 1991;Perks et al. 1992). This production is based on a Na¤-K¤-2Cl¦ cotransport system, probably located in type II cells (Strang, 1991). However, at birth it is vital for this process to be replaced by fluid reabsorption, and it is generally agreed that this is brought about by an amiloride-sensitive, Na¤-based transport system, probably augmented by colloid osmotic effects (Strang, 1991). The first agent shown to activate fluid reabsorption was adrenaline (sheep: Walters & Olver, 1978; goat: Perks & Cassin, 1989). However, in the guinea-pig, reabsorption can be produced by both adrenaline and noradrenaline, which, unlike the â_receptor activation in sheep, act through Journal of Physiology (1998), 513.1, pp. 283-294 283The effect of dopamine on lung liquid production by in vitro lungs from fetal guinea-pigs 1. The neuroendocrine system of the lungs has no clear function. However, previous studies of one of its products, somatostatin, have implicated it in lung liquid removal at birth. The present study extends this concept by investigating the effects of dopamine, a major product of this system, on lung liquid reabsorption. 2. The effects of dopamine on fetal lung liquid production and reabsorption were tested on in vitro lungs from fetal guinea-pigs of 60 ± 2 days of gestation (term = 67 days). Dopamine was placed in the outer bathing saline during the middle hour of 3 h incubations. Fluid movements across the pulmonary epithelium were monitored by a dye dilution method, and changes in rates over 1 h intervals were tested for significance by analysis of variance and regression analysis. 3. Dopamine was able to reduce fluid production or cause reabsorption (based on 42 preparations). Control preparations and those given 10¦Ì Ò dopamine showed no significant changes; those given higher concentrations showed significant reductions in production or reabsorption (P < 0·025 to P < 0·0005), according to dose (42·6 ± 10·8 % reduction at 10¦Ê Ò; 75·4 ± 5·9 % reduction at 10¦É Ò; 92·1 ± 7·0 % reduction at 10¦Ç Ò and 121·4 ± 12·8 % (reabsorption) at 10¦AE Ò dopamine). The linear log dose-response curve (r = 0·99) showed a theoretical threshold at 1·7 ² 10¦Í Ò dopamine. 4. Effects were mediated through specific dopamine receptors (based on 78 preparations).Dopamine at 10¦É Ò was tested together with each of three dopamine receptor antagonists at 10¦Ç Ò. The general dopamine receptor antagonist haloperidol and the more specific Dµ receptor blocker domperidone both abolished responses, but the D1 receptor antagonist SCH23390 was without effect. This suggested that Dµ dopamine receptors mediated the responses, and that responses were not due to conversion of dopamine to adrenaline or noradrenaline. 5. There was no evidence that responses involved amiloride-sensitive Na¤ transport (based on 54 preparat...

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Section: Methodsmentioning

confidence: 60%

Section: Quantification Of Results and Statistical Methodsmentioning

confidence: 99%

The effect of dopamine on lung liquid production by in vitro lungs from fetal guinea‐pigs

Chua

Perks

1998

The Journal of Physiology

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“…Fluid secretion into fetal lamb and guinea pig lungs decreases before birth (13,27,39,48) simultaneously with the appearance of endogenous catecholamines and stress hormones. ␤-Adrenoceptor agonist stimulation is thought to increase transepithelial Na ϩ transport by increasing ENaC activity at the apical side of alveolar epithelial type II cell (4) and by increasing the number and activity of the Na-KATPases in the basal membrane of the alveolar epithelial type II cell (42).…”

Section: Discussionmentioning

confidence: 99%

Oxytocin-induced labor augments IL-1β-stimulated lung fluid absorption in fetal guinea pig lungs

Nair¹,

Li²,

Bhattacharjee³

et al. 2005

American Journal of Physiology-Lung Cellular and Molecular Phys

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-We tested the hypothesis that oxytocin-induced labor augmented IL-1␤-induced/ -stimulated lung fluid absorption in preterm guinea pig fetuses. IL-1␤ was administered subcutaneously daily to timed-pregnant guinea pigs for 3 days with and without simultaneous cortisol synthesis inhibition by metyrapone. At day 3, oxytocin was administered, and fetuses were delivered by abdominal hysterotomy at 61 and by oxytocin-induced birth at 68 days gestation. Delivered fetuses were instilled with isosmolar 5% albumin into the lungs, and lung fluid movement was measured over 1 h by mass balance. Lung fluid absorption was induced in 61-day and stimulated in 68-day gestation lungs by IL-1␤. Labor induction by oxytocin augmented IL-1␤-induced/-stimulated lung fluid absorption. Metyrapone pretreatment did not affect oxytocin-induced/-stimulated lung fluid absorption, while completely blocking IL-1␤-induced/-stimulated fluid absorption. Fetal lung fluid absorption, when present, was always propranolol and amiloride sensitive, suggesting that ␤-adrenoceptor stimulation and amiloridesensitive sodium channels were critical for fluid absorption. Epithelial sodium channel and Na-K-ATPase subunit expressions were both increased by IL-1␤, but not further by oxytocin. Our results indicate that IL-1␤ release into the maternal blood circulation positively affects lung maturation due to the IL-1␤-induced release of cortisol and thus prepares the lungs for the epinephrine surge associated with labor.␤-adrenoceptors; cortisol; epinephrine; prenatal lung development; sodium transport CYTOKINES, SUCH AS INTERLEUKIN-1 (IL-1), can be important during pregnancy, because IL-1 has been detected in the placenta and amniotic fluid (12,44). In this regard, interleukins have been proposed as a signal for parturition onset, as cytokines can stimulate prostaglandin biosynthesis (41). During normal pregnancies, IL-1 is present in the amniotic fluid in low concentrations, but during preterm labor much higher amniotic fluid IL-1 concentrations are present (44). Intrauterine infection/inflammation may further elevate cytokine levels, the highest activity being attributable to IL-1␤ (44). Many prematurely born infants suffer from fetal infection and/or respiratory distress syndrome (RDS), both of which are important reasons for mortality of premature babies. Recent human data suggest that ion transport abnormalities across lung epithelial cells, i.e., an incomplete transition of lung fluid secretion to lung fluid absorption, can contribute to RDS development (1). Factors accelerating ion transport across alveolar cells may thus have benefits for the resolution of RDS. Recent experimental data have suggested that proinflammatory cytokines could also promote lung maturation (9,14,26,47). IL-1␣ increased mRNA surfactant protein expression and improved lung compliance in fetal rabbits (9). IL-1␣ also improved postnatal lung function with increased surfactant pool size without eliciting systemic inflammatory responses in lambs (14, 47). We recently reported that IL-...

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“…25 26 In brief, lung liquid production or reabsorption was measured by an impermeant tracer technique based on Blue Dextran 2000 (Pharmacia, Dorval, Que, Canada). Pregnant guinea pigs were anaesthetised with halothane, and the fetuses removed by caesarean section.…”

Section: Methodsmentioning

confidence: 99%

Effects of glucagon on in vitro liquid production by lungs from fetal guinea pigs

Choo

Liu

Perks

2000

Archives of Disease in Childhood - Fetal and Neonatal Edition

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Background-Lung liquid reabsorption in newborns with respiratory distress syndrome can be deficient. Respiratory distress syndrome is often seen in infants of diabetic mothers, in whom the neonatal surge of glucagon is suppressed. Aim-To investigate the possible eVects of glucagon on lung liquid reabsorption. Methods-Lungs from near term fetal guinea pigs (62 (2) days gestation; term = 67 days) were supported in vitro for three hours; lung liquid production and reabsorption were monitored by a dye dilution method. Conclusions-The results suggest that the surge of glucagon at birth may help to drain the lungs of fluid. As glucagon liberates cAMP, which also stimulates surfactant, glucagon is worth consideration for possible use in neonatal respiratory distress. (Arch Dis Child Fetal Neonatal Ed 2000;83:F28-F34) Results-Untreated

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Fluid production by in vitro lungs from fetal guinea pigs

Cited by 26 publications

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The effect of dopamine on lung liquid production by in vitro lungs from fetal guinea‐pigs

The effect of dopamine on lung liquid production by in vitro lungs from fetal guinea‐pigs

Oxytocin-induced labor augments IL-1β-stimulated lung fluid absorption in fetal guinea pig lungs

Effects of glucagon on in vitro liquid production by lungs from fetal guinea pigs

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