Mainstream cigarette smoke increases the permeability of human airways; however, the mechanism for this increased permeability is poorly defined. Tight junctions between adjacent epithelial cells constitute the physiological barrier to fluid and macromolecules in epithelium. These structures are highly regulated by phosphorylation and their association with the cytoskeleton. The goal of these studies was to identify the signal transduction pathways that regulate smoke-induced permeability. Using a physiologically relevant air-liquid interface exposure system, electrically tight monolayers of the human bronchial epithelial cell-line Calu-3 were exposed to fresh, whole mainstream cigarette smoke. This exposure results in a regulated, dose-dependent loss of epithelial barrier function in the lung epithelial monolayers. With cigarette smoke exposure, transepithelial electrical resistance (TER) is decreased and albumin flux is increased, indicating a loss in barrier function to ions and macromolecules, respectively; however, both largely recover in 30 min. Smoke-induced losses of macromolecular barrier function are the result of multicellular junctional reorganization, resulting in increased leak volume rather than leak frequency. Inhibiting Rho kinase (ROCK) significantly reduces the smoke-induced permeability to both ions and macromolecules, while inhibiting protein tyrosine kinases (PTK) only reduces smoke-induced macromolecular permeability. Interestingly, inhibiting myosin light chain kinase (MLCK) exacerbates smoke-induced permeability, indicating that MLCK and ROCK have opposing regulatory roles. Our results demonstrate that the smoke-induced loss of epithelial barrier function in human bronchial epithelium is a regulated process rather than a cytotoxic response. Additionally, our results indicate that activation of PTK and ROCK and inactivation of MLCK contribute to the increased airway permeability caused by mainstream cigarette smoke.

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The actions of ethanol on brain ligand-gated ion channels have important roles in the pathophysiology of alcohol-related neurodevelopmental disorders and fetal alcohol syndrome. Studies have shown that N-methyl-Daspartate (NMDA) receptors are among the ligand-gated ion channels affected by prenatal ethanol exposure. We exposed pregnant dams to an ethanol-containing liquid diet that results in blood ethanol levels near the legal intoxication limit in most states (0.08%). Primary cultures of hippocampal neurons were prepared from the neonatal offspring of these dams, and NMDA receptor function was assessed by patch clamp electrophysiological techniques after 6 -7 days in culture in ethanol-free media. Unexpectedly, we did not detect any changes in hippocampal NMDA receptor function at either the whole-cell or single-channel levels. However, we determined that fetal alcohol exposure alters the actions of the neurosteroids pregnenolone sulfate and pregnenolone hemisuccinate, which potentiate NMDA receptor function. Western immunoblot analyses demonstrated that this alteration is not due to a change in the expression levels of NMDA receptor subunits. Importantly, in utero ethanol exposure did not affect the actions of neurosteroids that inhibit NMDA receptor function. Moreover, the actions of pregnenolone sulfate on type A ␥-aminobutyric acid and non-NMDA receptor function were unaltered by ethanol exposure in utero, which suggests that the alteration is specific to NMDA receptors. These findings are significant because they provide, at least in part, a plausible mechanistic explanation for the alterations in the behavioral responses to neurosteroids found in neonatal rats prenatally exposed to ethanol and to other forms of maternal stress (Zimmerberg, B., and McDonald, B. C. (1996) Pharmacol. Biochem. Behav. 55, 541-547).Ingestion of ethanol during pregnancy can have profound effects on normal fetal development. These effects range from isolated alcohol-related birth defects to a combination of abnormalities that characterize the fetal alcohol syndrome (1). This syndrome is characterized by alterations in growth, facial and skull development, and central nervous system function. Fetal ethanol exposure produces long-lasting and debilitating neurobehavioral and neurophysiological dysfunctions such as deficits in learning, memory, information processing, and problem solving skills (2-5). Therefore, there is considerable interest in understanding the consequences of the teratogenic actions of ethanol in the central nervous system.Research from a number of laboratories suggests that the actions of ethanol on ligand-gated ion channels have important roles in the pathophysiology of alcohol-related neurodevelopmental disorders (for review, see Ref. 6). Experimental evidence indicates that glutamate receptors of the N-methyl-Daspartate (NMDA)1 subtype are among the ligand-gated ion channels affected by fetal exposure to ethanol. Studies have shown that fetal and/or neonatal ethanol exposure alters ligand binding to NMDA rece...

The present results suggest that kainate receptors are important targets for the actions of ethanol in the central nervous system.

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Phosgene (CG), a toxic inhalation and industrial hazard, causes bronchoconstriction, vasoconstriction and associated pathological effects that could be life threatening. Ion channels of the transient receptor potential (TRP) family have been identified to act as specific chemosensory molecules in the respiratory tract in the detection, control of adaptive responses and initiation of detrimental signaling cascades upon exposure to various toxic inhalation hazards (TIH); their activation due to TIH exposure may result in broncho- and vasoconstriction. We studied changes in the regulation of intracellular free Ca2+ concentration ([Ca2+]i) in cultures of human bronchial smooth muscle cells (BSMC) and human pulmonary microvascular endothelial cells (HPMEC) exposed to CG (16 ppm, 8 min), using an air/liquid interface exposure system. CG increased [Ca2+]i (p<0.05) in both cell types, The CG-induced [Ca2+]i was blocked (p<0.05) by two types of TRP channel blockers, SKF-96365, a general TRP channel blocker, and RR, a general TRPV (vanilloid type) blocker, in both BSMC and HPMEC. These effects correlate with the in vivo efficacies of these compounds to protect against lung injury and 24 hr lethality from whole body CG inhalation exposure in mice (8-10 ppm × 20 min). Thus the TRP channel mechanism appears to be a potential target for intervention in CG toxicity.

Available as a dietary supplement, black cohosh rhizome is most commonly marketed as a remedy for dysmenorrhea and menopausal symptoms. A previous subchronic toxicity study of black cohosh dried ethanolic extract (BCE) in female mice revealed a dose-dependent ineffective erythropoiesis with a macrocytosis consistent with the condition known as megaloblastic anemia. The purpose of this study was to investigate potential mechanisms by which BCE induces these particular hematological changes. B6C3F1/N female mice (32/group) were exposed by gavage to vehicle or 1000 mg/kg BCE for 92 days. Blood samples were analyzed for hematology, renal and hepatic clinical chemistry, serum folate and cobalamin, RBC folate, and plasma homocysteine and methylmalonic acid (MMA). Folate levels were measured in liver and kidney. Hematological changes included: decreased RBC count, increased MCV, and decreased reticulocyte, white blood cell, neutrophil and lymphocyte counts. Blood smear evaluation revealed increased Howell-Jolly bodies and occasional basophilic stippling in treated animals. Plasma homocysteine and MMA concentrations were increased in treated animals. Under the conditions of our study, BCE administration caused hematological and clinical chemistry changes consistent with a functional cobalamin, and possibly folate, deficiency. Further studies are needed to elucidate the mechanism by which BCE causes increases in homocysteine and MMA.

The present results suggest that kainate receptors are important targets for the actions of ethanol in the central nervous system.