The adenosine 2A receptor agonist GW328267C improves lung function after acute lung injury in rats.

There is a significant unmet need for treatments of patients with acute lung injury (ALI) and/or acute respiratory distress syndrome (ARDS). The primary mechanism that leads to resolution of alveolar and pulmonary edema is active vectorial Na(+) and Cl(-) transport across the alveolar epithelium. Several studies have suggested a role for adenosine receptors in regulating this fluid transport in the lung.

Phosphatidylinositol 4,5-bisphosphate stimulates alveolar epithelial fluid clearance in male and female adult rats.

Cell membrane phospholipids, like phosphatidylinositol 4,5-bisphosphate [PI(4,5)P(2)], can regulate epithelial Na channel (ENaC) activity. Gender differences in lung ENaC expression have also been demonstrated. However, the effects in vivo on alveolar fluid clearance are uncertain.

Fetal lung epithelial ion channels relocate in the cell membrane during late gestation.

Near the end of gestation, the direction of ion and fluid flow across the alveolar epithelium rapidly changes from secretion to absorption. Thus, the relative cell membrane location of epithelial Na channels (ENaCs) and cystic fibrosis transmembrane regulator (CFTR) Cl channels during late fetal lung development and after maternal interleukin-1β (IL-1β) pretreatment was the focus of our study. Western blot analysis after sucrose gradient separation of caveolin-1-(Cav-1)-rich membrane regions (CRR) and Cav-1-poor membrane (non-CRR) revealed primary CRR ENaC localization at gestation day (GD) 61 in guinea pigs.

Anthocyanin-rich black currant (Ribes nigrum L.) extract affords chemoprevention against diethylnitrosamine-induced hepatocellular carcinogenesis in rats.

Anthocyanins are known to possess potent anticarcinogenic properties against several cancers thus demonstrating potential for cancer prevention. Black currant (Ribes nigrum L., Grossulariaceae) fruits have a high anthocyanin content.

Lung fluid absorption is induced in preterm guinea pigs ventilated with low tidal volumes.

The objective of this study was to determine if low tidal volume (V(t)) ventilation was beneficial when ventilating preterm fetuses. The authors ventilated preterm guinea pig fetuses at gestation day (GD) 67, 3 days before birth, newborn, and 10-day-old (PD10) guinea pigs with low V(t) (6 mL/kg body weight [bw]) and compared them to age-matched fetuses/animals ventilated with higher potentially injurious V(t) (12 mL/kg bw). Lung fluid absorption was measured after intratracheal instillation of 5% albumin in 0.

Beta-adrenoceptor stimulation of alveolar fluid clearance is increased in rats with heart failure.

The alveolar epithelium plays a critical role in resolving pulmonary edema. We thus hypothesized that its function might be upregulated in rats with heart failure, a condition that severely challenges the lung's ability to maintain fluid balance. Heart failure was induced by left coronary artery ligation.

IL-1beta-induced cortisol stimulates lung fluid absorption in fetal guinea pigs via SGK-mediated Nedd4-2 inhibition.

We tested the hypothesis that interleukin (IL)-1beta-induced cortisol synthesis stimulates distal lung fluid absorption in fetal guinea pigs via induction of serum- and glucocorticoid-regulated kinase (SGK) and inhibition of neural precursor cell expressed, developmentally downregulated protein 4-2 (Nedd4-2). IL-1beta was subcutaneously administered daily to timed-pregnant guinea pigs over 3 days. Fetuses were obtained by abdominal hysterotomy at gestation day (GD)61 and GD68 and instilled with an isosmolar 5% albumin solution into the lungs.

Delineation of VEGF-regulated genes and functions in the cervix of pregnant rodents by DNA microarray analysis.

Background: VEGF-regulated genes in the cervices of pregnant and non-pregnant rodents (rats and mice) were delineated by DNA microarray and Real Time PCR, after locally altering levels of or action of VEGF using VEGF agents, namely siRNA, VEGF receptor antagonist and mouse VEGF recombinant protein.

Methods: Tissues were analyzed by genome-wide DNA microarray analysis, Real-time and gel-based PCR, and SEM, to decipher VEGF function during cervical remodeling. Data were analyzed by EASE score (microarray) and ANOVA (Real Time PCR) followed by Scheffe's F-test for multiple comparisons.

RNA interference for CFTR attenuates lung fluid absorption at birth in rats.

Background: Small interfering RNA (siRNA) against alphaENaC (alpha-subunit of the epithelial Na channel) and CFTR (cystic fibrosis transmembrane conductance regulator) was used to explore ENaC and CTFR function in newborn rat lungs.

Methods: Twenty-four hours after trans-thoracic intrapulmonary (ttip) injection of siRNA-generating plasmid DNA (pSi-0, pSi-4, or pSi-C2), we measured CFTR and ENaC expression, extravascular lung water, and mortality.

Results: alphaENaC and CFTR mRNA and protein decreased by approximately 80% and approximately 85%, respectively, following alphaENaC and CFTR silencing.

Involvement of {alpha}ENaC and Nedd4-2 in the conversion from lung fluid secretion to fluid absorption at birth in the rat as assayed by RNA interference analysis.

To explore interactions between the epithelial Na channel (ENaC) and neural precursor expressed, developmentally downregulated protein 4-2 (Nedd4-2) at the conversion of the rat lung from fluid secretion to absorption at birth, we used small-interfering RNA (siRNA) against alphaENaC and Nedd4-2. siRNA-generating plasmid DNA (pDNA) was administered via trans-thoracic intrapulmonary (ttip) injection 24 h before ENaC and Nedd4-2 expression, extravascular lung water, and mortality were measured. alphaENaC mRNA and protein were specifically reduced by approximately 65% after pSi-4 injection.

Stimulation of MAP kinase pathways after maternal IL-1beta exposure induces fetal lung fluid absorption in guinea pigs.

Background: We tested the hypothesis that maternal interleukin-1beta (IL-1beta) pretreatment and induction of fetal cortisol synthesis activates MAP kinases and thereby affects lung fluid absorption in preterm guinea pigs.

Methods: IL-1beta was administered subcutaneously daily to timed-pregnant guinea pigs for three days. Fetuses were obtained by abdominal hysterotomy and instilled with isosmolar 5% albumin into the lungs and lung fluid movement was measured over 1 h by mass balance.

A noninflammatory interleukin-1beta fragment stimulates fetal lung fluid absorption in guinea pigs.

We have previously demonstrated that full-length interleukin (IL)-1beta can induce and stimulate lung fluid absorption in near-term guinea pig fetuses via stimulation of fetal cortisol synthesis and release. To develop a potentially clinically useful drug, we tested the hypothesis that maternal administration of a noninflammatory IL-1beta-fragment (IL-1beta(Fr)) induced cortisol synthesis and stimulated lung fluid absorption in preterm fetuses. IL-1beta(Fr) was administered s.

Integrating acute lung injury and regulation of alveolar fluid clearance.

The acute respiratory distress syndrome (ARDS) is characterized by non-cardiogenic pulmonary edema and flooding of the alveolar air spaces with proteinaceous fluid. ARDS develops in response to inflammatory stresses including sepsis, trauma, and severe pneumonia, and despite aggressive critical care management, it still has a mortality of 30-50%. At the time of its original description in 1967, relatively little was known about the specific mechanisms by which the alveolar epithelium regulated lung fluid balance.

Impaired alveolar liquid clearance after 48-h isoproterenol infusion spontaneously recovers by 96 h of continuous infusion.

We previously demonstrated that 48-h isoproterenol (Iso) infusion in rats impaired the ability of beta-adrenoceptor (beta-AR) agonists to increase alveolar liquid clearance (ALC). In this study, we determined whether this impairment persisted over longer time periods by infusing 400 mug.kg(-1).

Protective effect of endogenous beta-adrenergic tone on lung fluid balance in acute bacterial pneumonia in mice.

Some investigators have reported that endogenous beta-adrenoceptor tone can provide protection against acute lung injury. Therefore, we tested the effects of beta-adrenoceptor inhibition in mice with acute Escherichia coli pneumonia. Mice were pretreated with propranolol or saline and then intratracheally instilled with live E.

RNA interference for alpha-ENaC inhibits rat lung fluid absorption in vivo.

We used siRNA against the alpha-ENaC (epithelial Na channel) subunit to investigate ENaC involvement in lung fluid absorption in rats by the impermeable tracer technique during baseline and after beta-adrenoceptor stimulation by terbutaline. Terbutaline stimulation of lung fluid absorption increased fluid absorption by 165% in pSi-0-pretreated rat lungs (irrelevant siRNA-generating plasmid). Terbutaline failed to increase lung fluid absorption in rats given the specific alpha-ENaC siRNA-generating plasmid (pSi-4).

Congenital diaphragmatic hernia prevents absorption of distal air space fluid in late-gestation rat fetuses.

We hypothesized that congenital diaphragmatic hernia (CDH) may decrease distal air space fluid absorption due to immaturity of alveolar epithelial cells from a loss of the normal epithelial Na+ transport, as assessed by amiloride and epithelial Na+ channel (ENaC) and Na-K-ATPase expression, as well as failure to respond to endogenous epinephrine as assessed by propranolol. Timed-pregnant dams were gavage fed 100 mg of nitrofen at 9.5-day gestation to induce CDH in the fetuses, and distal air space fluid absorption experiments were carried out on 22-day gestation (term) fetuses.

Type VI collagen induces cardiac myofibroblast differentiation: implications for postinfarction remodeling.

Cardiac fibroblast (CF) proliferation and differentiation into hypersecretory myofibroblasts can lead to excessive extracellular matrix (ECM) production and cardiac fibrosis. In turn, the ECM produced can potentially activate CFs via distinct feedback mechanisms. To assess how specific ECM components influence CF activation, isolated CFs were plated on specific collagen substrates (type I, III, and VI collagens) before functional assays were carried out.

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

We tested the hypothesis that oxytocin-induced labor augmented IL-1beta-induced/-stimulated lung fluid absorption in preterm guinea pig fetuses. IL-1beta 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.

PKA delivery to the distal lung air spaces increases alveolar liquid clearance after isoproterenol-induced alveolar epithelial PKA desensitization.

Isoproterenol (Iso) infusion for 48 h in rats decreases the ability of beta-adrenoceptor (beta-AR) agonists to increase alveolar liquid clearance (ALC). An impairment in protein kinase A (PKA) function appears to be critical in producing the desensitized ALC response. To test this hypothesis, we used a novel protein delivery reagent (Chariot, Active Motif) to deliver either the PKA catalytic subunit or the PKA holoenzyme to the distal lung epithelium of Iso-infused rats (400 microg.

Stimulation of distal airspace fluid clearance in guinea pigs involves bumetanide-sensitive ion transport.

Objective: This study was undertaken to test the hypothesis that beta-adrenoceptor stimulation of fetal lung fluid absorption in near-term guinea pig fetuses involves bumetanide-sensitive ion transport.

Study Design: Fetuses were obtained from timed-pregnant guinea pigs at 61 to 69 days' gestation with and without oxytocin-induced preterm labor. The fetuses were placed on continuous positive airway pressure oxygenation, and an isosmolar 5% albumin solution was instilled into the lungs.

Mechanisms of alveolar protein clearance in the intact lung.

Transport of protein across the alveolar epithelial barrier is a critical process in recovery from pulmonary edema and is also important in maintaining the alveolar milieu in the normal healthy lung. Various mechanisms have been proposed for clearing alveolar protein, including transport by the mucociliary escalator, intra-alveolar degradation, or phagocytosis by macrophages. However, the most likely processes are endocytosis across the alveolar epithelium, known as transcytosis, or paracellular diffusion through the epithelial barrier.

IL-1beta stimulates alveolar fluid absorption in fetal guinea pig lungs via the hypothalamus-pituitary-adrenal gland axis.

We tested the hypothesis that interleukin (IL)-1beta-induced cortisol synthesis stimulates alveolar fluid clearance in preterm fetuses. IL-1beta was administered subcutaneously daily to timed-pregnant guinea pigs for 3 days with and without simultaneous cortisol synthesis inhibition by metyrapone. Fetuses were obtained by abdominal hysterotomy at 61 and 68 days gestation and instilled with isosmolar 5% albumin in the lungs, and alveolar fluid movement was measured over 1 h from the change in alveolar protein concentration.