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Thyroid hormone (T3) increases Na-K-ATPase activity in rat adult alveolar type II cells via a PI3Kdependent pathway. In these cells, dopamine and [beta]-adrenergic agonists can stimulate Na-K-ATPase activity through either PI3K or MAPK pathways. We assessed the role of the MAPK pathway in the stimulation of Na-K-ATPase by T3. In the adult rat alveolar type II-like cell line MP48, T3 enhanced MAPK/ERK1/2 activity in a dose-dependent manner. Increased ERK1/2 phosphorylation was observed within 5 min, peaked at 20 min, and then decreased. Two MEK1/2 inhibitors, U0126 and PD-98059, each abolished the T3-induced increase in the quantity of Na-K-ATPase [[alpha].sub.1]-subunit plasma membrane protein and Na-K-ATPase activity. T3 also increased the phosphorylation of MAPK/p38; however, SB-203580, a specific inhibitor of MAPK/p38 activity, did not prevent the T3-induced Na-K-ATPase activity. SP-600125, a specific inhibitor of the MAPK/JNK pathway, also did not block the T3-induced Na-K-ATPase activity. Phorbol 12-myristate 13-acetate (PMA) significantly increased ERK1/2 phosphorylation and Na-K-ATPase activity. The PMA-induced Na-K-ATPase activity was inhibited by U0126. These data indicate that activation of MAPK-ERK1/2 was required for the T3-induced increase in Na-K-ATPase activity in addition to the requirement for the PI3K pathway. thyroid hormone

Late in gestation, the developing air space epithelium switches from chloride and fluid secretion to sodium and fluid absorption. Absorption requires Na-KATPase acting in combination with apical sodium entry mechanisms. Hypothyroidism inhibits perinatal fluid resorption, and thyroid hormone [triiodothyronine (T3)] stimulates adult alveolar epithelial cell (AEC) Na-K-ATPase. This study explored the developmental regulation of Na-K-ATPase by T3 in fetal rat distal lung epithelial (FDLE) ceils. T3 increased Na-K-ATPase activity in primary FDLE cells from gestational day 19 [both primary FDLE cells at embryonic day 19 (E19) and the cell line FD19 derived from FDLE cells at E19]. However, T3 did not increase the Na-K-ATPase activity in less mature FDLE cells, including primary E17 and E18 FDLE cells and the cell line FD18 (derived from FDLE cells at E18). Subsequent experiments assessed the T3 signal pathway to define whether it was similar in the late FDLE and adult AEC and to determine the site of the switch in responsiveness to T3. As in adult AEC, in the FD19 cell fine, the phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin blocked the T3-induced increase in Na-K-ATPase activity and plasma membrane quantity. T3 caused a parallel increase in phosphorylation of Akt at Ser473 in FDLE cells from E19, but not from E17 or E18. In the FD18 cell line, transient expression of a constitutively active mutant of the PI3K catalytic pll0 subunit significantly augmented the Na-K-ATPase activity and the cell surface expression of Na-KATPase [[alpha].sub.1] protein. In conclusion, FDLE cells from E17 and E18 lacked T3-sensitive Na-K-ATPase activity but acquired this response at E19. The developmental stimulation of Na-K-ATPase by T3 in rat FDLE cells requires activation of PI3K, and the acquisition of T3 responsiveness may be at PI3K or upstream in the signaling pathway. triiodothyronine

Na-K-ATPase protein is critical for maintaining cellular ion gradients and volume and for transepithelial ion transport in kidney and lung. Thyroid hormone, 3,3',5-triiodo-L-thyronine ([T.sub.3]), given for 2 days to adult rats, increases alveolar fluid resorption by 65%, but the mechanism is undefined. We tested the hypothesis that [T.sub.3] stimulates Na-K-ATPase in adult rat alveolar epithelial cells (AEC), including primary rat alveolar type II (ATII) cells, and determined mechanisms of the [T.sub.3] effect on the Na-KATPase enzyme using two adult rat AEC cell lines (MP48 and RLE-6TN). [T.sub.3] at [10.sup.-8] and [10.sup.-5] M increased significantly hydrolytic activity of Na-K-ATPase in primary ATII cells and both AEC cell lines. The increased activity was dose dependent in the cell lines ([10.sup.-9]-[10.sup.-4] M) and was detected within 30 min and peaked at 6 h. Maximal increases in Na-K-ATPase activity were twofold in MP48 and RLE-6TN cells at pharmacological [T.sub.3] of [10.sup.-5] and [10.sup.-4] M, respectively, but increases were statistically significant at physiological [T.sub.3] as low as [10.sup.-9] M. This effect was [T.sub.3] specific, because reverse T3 (3,3',5'-triiodo-L-thyronine) at [10.sup.-9]-[10.sub.-4] M had no effect. The [T.sub.3]-induced increase in Na-K-ATPase hydrolytic activity was not blocked by actinomycin D. No significant change in mRNA and total cell protein levels of Na-K-ATPase were detected with [10.sup.-9]-[10.sup.-5] M [T.sub.3] at 6 h. However, [T.sub.3] increased cell surface expression of Na-K-ATPase [[alpha].sub.1]- or [[beta].sub.1]-Subunit proteins by 1.7- and 2-fold, respectively, and increases in Na-K-ATPase activity and cell surface expression were abolished by brefeldin A. These data indicate that [T.sub.3] specifically stimulates Na-K-ATPase activity in adult rat AEC. The up-regulation involves translocation of Na-K-ATPase to plasma membrane, not increased gene transcription. These results suggest a novel nontranscriptional mechanism for regulation of Na-K-ATPase by thyroid hormone. alveolar cell lines; protein translocation; sodium pump

[Na.sup.+]-[K.sup.+]-ATPase plays an essential role in active alveolar epithelial fluid resorption. In fetal and adult alveolar epithelial cells, glucocorticoids (GC) increase [Na.sup.+]-[K.sup.+]-ATPase activity and mRNA levels. We sought to define the mechanism of [Na.sup.+]-[K.sup.+]-ATPase gene upregulation by GC. In a rat alveolar epithelial cell line (RLE), dexamethasone (Dex) increased [[beta].sup.1]-subunit [Na.sup.+]-[K.sup.+]-ATPase mRNA expression two- to threefold within 3 h after exposure to the GC. The increased gene expression was due to increased transcription as demonstrated by nuclear run-on assays, whereas mRNA stability remained unchanged. Transient transfection of 5' deletion mutants of a [[beta].sub.1] promoter-reporter construct demonstrated a 1.5- to 2.2-fold increase in promoter activity by Dex. All of the 5' deletion constructs contained partial or palindromic GC regulatory elements (GRE) and responded to GC. The increased expression of promoter reporter was inhibited by RU-486, a GC receptor (GR) antagonist, suggesting the involvement of GR. The palindromic GRE at -631 demonstrated Dex induction in a heterologous promoter construct. Gel mobility shift assays using RLE nuclear extracts demonstrated specific binding to this site and the presence of GR. We conclude that GC directly stimulate transcription of [Na.sup.+]-[K.sup.+]-ATPase [[beta].sub.1] gene expression in adult rat lung epithelial cells through a GR-dependent mechanism that can act at multiple sites. sodium pump; glucocorticoid receptor; glucocorticoid response element; promoter; alveolar fluid; ion transport; type II cells

Whole cell perforated patchclamp experiments were performed with adult rat alveolar epithelial cells. The holding potential was -60 mV, and depolarizing voltage steps activated voltage-gated [K.sup.+] (Ky) channels. The voltage-activated currents exhibited a mean reversal potential of -32 reV. Complete activation was achieved at -10 mV. The currents exhibited slow inactivation, with significant variability in the time course between cells. Tail current analysis revealed cell-to-cell variability in [K.sup.+] selectivity, suggesting contributions of multiple Kv [alpha]-subunits to the whole cell current. The Kv channels also displayed steady-state inactivation when the membrane potential was held at depolarized voltages with a window current between -30 and 5 mV. Analysis of RNA isolated from these cells by RT-PCR revealed the presence of eight Kv [alpha]-subunits (Kv1.1, Kv1.3, Kv 1.4, Kv2.2, Kv4.1, Kv4.2, Kv4.3, and Kv9.3), three [beta]-subunits (Kv[beta]l.1, Kv[beta]2.1, and Kv[beta]3.1), and two [K.sup.+] channel interacting protein (KChIP) isoforms (KChIP2 and KChIP3). Western blot analysis with available Kv [alpha]-subunit antibodies (Kv1.1, Kv1.3, Kv1.4, Kv4.2, and Kv4.3) showed labeling of 50-kDa proteins from alveolar epithelial cells grown in monolayer culture. Immunocytochemical analysis of cells from monolayers showed that Kv1.1, Kv1.3, Kv1.4, Kv4.2, and Kv4.3 were localized to the apical membrane. We conclude that expression of multiple Kv [alpha]-, [beta]-, and KChIP subunits explains the variability in inactivation gating and [K.sup.+] selectivity observed between cells and that Kv channels in the apical membrane may contribute to basal [K.sup.+] secretion across the alveolar epithelium. voltage-gated potassium channels; potassium ion secretion; oxygen-sensitive potassium channels; alveolar fluid clearance

The recently discovered Omicron variant of SARS-CoV-2 has rapidly burst into the public and scientific eye, being detected in more than 26 countries around the world. Given its more than 50 mutations, there is widespread concern about its public health impact, leading theWorld Health Organization to designate it a variant of concern. This Commentary provides a summary of current knowledge and unknowns about this viral variant as of December 2, 2021 and summarizes the key questions that need to be rapidly answered. [ABSTRACT FROM AUTHOR]

Clinical and Translational Science Award (CTSA) TL1 trainees and KL2 scholars were surveyed to determine the immediate impact of the COVID-19 pandemic on training and career development. The most negative impact was lack of access to research facilities, clinics, and human subjects, plus for KL2 scholars lack of access to team members and need for homeschooling. TL1 trainees reported having more time to think and write. Common strategies to maintain research productivity involved time management, virtual connections with colleagues, and shifting to research activities not requiring laboratory/clinic settings. Strategies for mitigating the impact of the COVID-19 pandemic on training and career development are described. [ABSTRACT FROM AUTHOR]

Background: In order to conduct translational science, scientists must combine domain-specific expertise with knowledge on how to identify and cross translational hurdles, and insights on positioning discoveries for the next translational stage. Expert educators from the Clinical and Translational Science Awards (CTSA) Consortium identified 97 knowledge, skills, and abilities (KSAs) important to include in training programs for translational scientists. To assist educators and trainees to use these KSAs, a conceptual model called "Personalized Pathways" was developed that prioritizes KSAs based on trainee background, research area, or phenotype, and expertise on the research team. Purpose: To understand how CTSA educators prioritize specific KSAs when developing personalized training plans for different translational phenotypes and to identify areas of similarity and difference across phenotypes. Methods: A web-based, cross-sectional survey of CTSA educators was done. For a selected phenotype, respondents recommended one of four levels of mastery for each of the 97 KSAs. Results were tabulated by frequency, weighted by importance, and divided into tertiles representing high, middle, and lower priority KSAs. Agreement across phenotypes was compared using Krippendorff's alpha. Results: Ten KSAs were high training priority for Preclinical, Clinical, and Community-Engaged phenotypes. These address research methods, responsible conduct of research, team building, and communicating research results. Nine KSAs were in the next tertile for priority reflecting KSAs in biostatistics, bioinformatics, regulatory precepts, and translating implications of research findings. Conclusion: A smaller set of KSAs can be prioritized for training Preclinical-, Clinical-, and Community-Engaged researchers. Future work should explore this approach for other phenotypes. [ABSTRACT FROM AUTHOR]

During the 2020 Spring Festival in China, the outbreak of a novel coronavirus, named COVID‐19 by WHO, brought on a worldwide panic. According to the clinical data of infected patients, radiologic evidence of lung edema is common and deserves clinical attention. Lung edema is a manifestation of acute lung injury (ALI) and may progress to hypoxemia and potentially acute respiratory distress syndrome (ARDS). Patients diagnosed with ARDS have poorer prognosis and potentially higher mortality. Although no effective treatment is formally approved for COVID‐19 infection, support of ventilation with oxygen therapy and sometimes mechanical ventilation is often required. Treatment with systemic and/or local glucocorticoids might be helpful to alleviate the pulmonary inflammation and edema, which may decrease the development and/or consequences of ARDS. In this article, we focus on the lung edema and ALI of patients with this widely transmitted COVID‐19 infection in order to provide clinical indications and potential therapeutic targets for clinicians and researchers. [ABSTRACT FROM AUTHOR]

Acute Respiratory Distress Syndrome (ARDS) continues to have a high mortality. Currently, there are no biomarkers that provide reliable prognostic information to guide clinical management or stratify risk among clinical trial participants. The objective of this study was to probe the bronchoalveolar lavage fluid (BALF) proteome to identify proteins that differentiate survivors from non-survivors of ARDS. Patients were divided into early-phase (1 to 7 days) and late-phase (8 to 35 days) groups based on time after initiation of mechanical ventilation for ARDS (Day 1). Isobaric tags for absolute and relative quantitation (iTRAQ) with LC MS/MS was performed on pooled BALF enriched for medium and low abundance proteins from early-phase survivors (n = 7), early-phase non-survivors (n = 8), and late-phase survivors (n = 7). Of the 724 proteins identified at a global false discovery rate of 1%, quantitative information was available for 499. In early-phase ARDS, proteins more abundant in survivors mapped to ontologies indicating a coordinated compensatory response to injury and stress. These included coagulation and fibrinolysis; immune system activation; and cation and iron homeostasis. Proteins more abundant in early-phase non-survivors participate in carbohydrate catabolism and collagen synthesis, with no activation of compensatory responses. The compensatory immune activation and ion homeostatic response seen in early-phase survivors transitioned to cell migration and actin filament based processes in late-phase survivors, revealing dynamic changes in the BALF proteome as the lung heals. Early phase proteins differentiating survivors from non-survivors are candidate biomarkers for predicting survival in ARDS. [ABSTRACT FROM AUTHOR]

In rodent model systems, the sequential changes in lung morphology resulting from hyperoxic injury are well characterized and are similar to changes in human acute respiratory distress syndrome. In the injured lung, alveolar type two (AT2) epithelial cells play a critical role in restoring the normal alveolar structure. Thus characterizing the changes in AT2 cells will provide insights into the mechanisms underpinning the recovery from lung injury. We applied an unbiased systems-level proteomics approach to elucidate molecular mechanisms contributing to lung repair in a rat hyperoxic lung injury model. AT2 cells were isolated from rat lungs at predetermined intervals during hyperoxic injury and recovery. Protein expression profiles were determined by using iTRAQ with tandem mass spectrometry. Of the 959 distinct proteins identified, 183 significantly changed in abundance during the injury-recovery cycle. Gene ontology enrichment analysis identified cell cycle, cell differentiation, cell metabolism, ion homeostasis, programmed cell death, ubiquitination, and cell migration to be significantly enriched by these proteins. Gene set enrichment analysis of data acquired during lung repair revealed differential expression of gene sets that control multicellular organismal development, systems development, organ development, and chemical homeostasis. More detailed analysis identified activity in two regulatory pathways, JNK and miR 374. A novel short time-series expression miner algorithm identified protein clusters with coherent changes during injury and repair. We concluded that coherent changes occur in the AT2 cell proteome in response to hyperoxic stress. These findings offer guidance regarding the specific molecular mechanisms governing repair of the injured lung. [ABSTRACT FROM AUTHOR]

We previously reported that the 3,5,3′-triiodo-l-thyronine (T3)-induced increase of Na-K-ATPase activity in rat alveolar epithelial cells (AECs) required activation of Src kinase, PI3K, and MAPK/ERK½. In the present study, we assessed the role of Akt in Na-K-ATPase activity and the interaction between the PI3K and MAPK in response to T3 by using MP48 cells, inhibitors, and constitutively active mutants in the MP48 (alveolar type II-like) cell line. The Akt inhibitor VIII blocked T3-induced increases in Na-K-ATPase activity and amount of plasma membrane Na-K-ATPase protein. The Akt inhibitor VIII also abolished the increase in Na-K-ATPase activity induced by constitutively active mutants of either Src kinase or PI3K. Moreover, constitutively active mutants of Akt increased Na-K-ATPase activity in the absence of T3. Thus activation of Akt was required for T3-induced Na-K-ATPase activity in AECs and is sufficient in the absence of T3. Inhibitors of Src kinase (PP1), PI3K (wortmannin), and ERK½ (U0126) all blocked the T3-induced Na-K-ATPase activity. PP1 blocked the activation of PI3K and also ERK½ by T3, whereas U0126 did not prevent T3 activation of Src kinase or PI3K activity. Wortmannin did not significantly alter T3-increased MAPK/ERK½ activity, suggesting that T3-activated PI3K/Akt and MAPK/ERK½ pathways acted downstream of the Src kinase. Furthermore, in the absence of T3, a constitutively active mutant of Src kinase increased activities of Na-K-ATPase, PI3K, and MAPK/ERK½. A constitutively active mutant of PI3K enhanced Na-K-ATPase activity but did not alter the MAPK/ERK½ activity significantly. In summary, in adult rat AECs T3-stimulated Src kinase activity can activate both PI3K/Akt and MAPK/ERK½, and activation of Akt is necessary for T3-induced Na-K-ATPase activity. [ABSTRACT FROM AUTHOR]

Lei J, Mariash CN, Bhargava M, Wattenberg EV, Ingbar DH. T3 increases Na-K-ATPase activity via a MAPK/ERK 1/2-dependent pathway in rat adult alveolar epithelial cells. Am J Physiol Lung Cell Mol Physiol 294: L749-L754, 2008. First published January 25, 2008; doi: 10.11 52/ajplung.00335.2007.-Thyroid hormone (T3) increases Na-K-ATPase activity in rat adult alveolar type II cells via a P13K- dependent pathway. In these cells, dopamine and ~3-adrenergic ago- fists can stimulate Na-K-ATPase activity through either P13K or MAPK pathways. We assessed the role of the MAPK pathway in the stimulation of Na-K-ATPase by T3. In the adult rat alveolar type Il-like cell line MP48, T3 enhanced MAPKIERKI/2 activity in a dose-dependent manner. Increased ERKI/2 phosphorylation was ob- served within 5 mm, peaked at 20 mm, and then decreased. Two MEKI/2 inhibitors, U0126 and PD-98059, each abolished the T3- induced increase in the quantity of Na-K-ATPase ci1-subunit plasma membrane protein and Na-K-ATPase activity. T3 also increased the phosphorylation of MAPKIp38; however, SB-203580, a specific inhib- itor of MAPK/p38 activity, did not prevent the T3-induced Na-K-ATPase activity. SP-600 125, a specific inhibitor of the MAPKIJNK pathway, also did not block the T3-induced Na-K-ATPase activity. Phorbol 12-myris- tate I 3-acetate (PMA) significantly increased ERK1/2 phosphorylation and Na-K-ATPase activity. The PMA-induced Na-K-ATPase activity was inhibited by U0 126. These data indicate that activation of MAPK- ERKI/2 was required for the T3-induced increase in Na-K-ATPase activity in addition to the requirement for the P13K pathway. [ABSTRACT FROM AUTHOR]

Late in gestation, the developing air space epithelium switches from chloride and fluid secretion to sodium and fluid absorption. Absorption requires Na-K- ATPase acting in combination with apical sodium ently mechanisms. Hypothymidism inhibits perinatal fluid resorption, and thyroid hormone [triiodothymnine (T3)] stimulates adult alveolar epithelial cell (AEC) Na-K-ATPase. This study explored the developmental regulation of Na-K-ATPase by T3 in fetal rat distal lung epithelial (FDLE) cells. T3 increased Na-K-ATPase activity in primary FDLE cells from gestational day 19 [both primary FDLE cells at embryonic day 19 (E19) and the cell line FD19 derived from FDLE cells at E19]. However, 13 did not increase the Na-K-ATPase activity in less mature FDLE cells, including primary E17 and E18 FDLE cells and the cell line FD18 (derived from FDLE cells at E18). Subsequent experiments assessed the T3 signal pathway to define whether it was similar in the late FDLE and adult AEC and to determine the site of the switch in responsiveness to T3. As in adult AEC, in the FD19 cell line, the phosphatidylinositol 3-kinase (P13K) inhibitor wortmannin blocked the 13-induced increase in Na-K-ATPase activity and plasma membrane quantity. T3 caused a parallel increase in phosphotylation of Akt at Ser473 in FDLE cells at E19, but not from E17 or E18. In the FD18 cell line, transient expression of a constitutively active mutant of the P13K catalytic p110 subunit significantly augmented the Na-K-ATPase activity and the cell surface expression of Na-K-ATPase α1 protein. In conclusion, FDLE cells from E17 and E18 lacked 13-sensitive Na-K-ATPase activity but acquired this response at E19. The developmental stimulation of Na-K-ATPase by 13 in rat FDLE cells requires activation of P13K, and the acquisition of 13 responsiveness may be at P13K or upstream in the signaling pathway. [ABSTRACT FROM AUTHOR]

Na-K-ATPase protein is critical for maintaining cellular ion gradients and volume and for transepithelial ion transport in kidney and lung. Thyroid hormone, 3,3',5-triiodo-L-thyronine (T[sub 3]), given for 2 days to adult rats, increases alveolar fluid resorption by 65%, but the mechanism is undefined. We tested the hypothesis that T[sub 3] stimulates Na-K-ATPase in adult rat alveolar epithelial cells (AEC), including primary rat alveolar type II (ATII) cells, and determined mechanisms of the T[sub 3] effect on the Na-KATPase enzyme using two adult rat AEC cell lines (MP48 and RLE-6TN). T[sub 3] at 10[sup -8] and 10[sup -5] M increased significantly hydrolytic activity of Na-K-ATPase in primary ATII cells and both AEC cell lines. The increased activity was dose dependent in the cell lines (10[sup -9]-10[sup -4] M) and was detected within 30 min and peaked at 6 h. Maximal increases in Na-K-ATPase activity were twofold in MP48 and RLE-6TN cells at pharmacological T[sub 3] of 10[sup -5] and 10[sup -4] M, respectively, but increases were statistically significant at physiological T[sub 3] as low as 10[sup -9] M. This effect was T[sub 3] specific, because reverse T[sub 3] (3,3',5'-triiodo-L-thyronine) at 10[sup -9]-10[sup -4] M had no effect. The T[sub 3]-induced increase in Na-K-ATPase hydrolytic activity was not blocked by actinomycin D. No significant change in mRNA and total cell protein levels of Na-K-ATPase were detected with 10[sup -9]-10[sup -5] M T[sub 3] at 6 h. However, T[sub 3] increased cell surface expression of Na-K-ATPase α[sub 1]- or β[sub 1]-subunit proteins by 1.7- and 2-fold, respectively, and increases in Na-K-ATPase activity and cell surface expression were abolished by brefeldin A. These data indicate that T[sub 3] specifically stimulates Na-K-ATPase activity in adult rat AEC. The upregulation involves translocation of Na-K-ATPase to plasma membrane, not increased gene transcription. These results suggest a novel nontranscriptional mechanism for regulation of Na-K-ATPase by thyroid hormone. [ABSTRACT FROM AUTHOR]

Na[sup +]-K[sup +]-ATPase plays an essential role in active alveolar epithelial fluid resorption. In fetal and adult alveolar epithelial cells, glucocorticoids (GC) increase Na[sup +]-K[sup +]-ATPase activity and mRNA levels. We sought to define the mechanism of Na[sup +]-K[sup +]-ATPase gene upregulation by GC. In a rat alveolar epithelial cell line (RLE), dexamethasone (Dex) increased β[sub 1]-subunit Na[sup +]-K[sup +]-ATPase mRNA expression two- to three-fold within 3 h after exposure to the GC. The increased gene expression was due to increased transcription as demonstrated by nuclear run-on assays, whereas mRNA stability remained unchanged. Transient transfection of 5' deletion mutants of a β[sub 1] promoter-reporter construct demonstrated a 1.5- to 2.2-fold increase in promoter activity by Dex. All of the 5' deletion constructs contained partial or palindromic GC regulatory elements (GRE) and responded to GC. The increased expression of promoter reporter was inhibited by RU-486, a GC receptor (GR) antagonist, suggesting the involvement of GR. The palindromic GRE at -631 demonstrated Dex induction in a heterologous promoter construct. Gel mobility shift assays using RLE nuclear extracts demonstrated specific binding to this site and the presence of GR. We conclude that GC directly stimulate transcription of Na[sup +]-K[sup +]-ATPase β[sub 1] gene expression in adult rat lung epithelial cells through a GR-dependent mechanism that can act at multiple sites. [ABSTRACT FROM AUTHOR]

Whole cell perforated patchclamp experiments were performed with adult rat alveolar epithelial cells. The holding potential was -60 mV, and depolarizing voltage steps activated voltage-gated K[sup +] (Kv) channels. The voltage-activated currents exhibited a mean reversal potential of -32 mV. Complete activation was achieved at -10 mV. The currents exhibited slow inactivation, with significant variability in the time course between cells. Tail current analysis revealed cell-to-cell variability in K[sup +] selectivity, suggesting contributions of multiple Kv α-subunits to the whole cell current. The Kv channels also displayed steady-state inactivation when the membrane potential was held at depolarized voltages with a window current between -30 and 5 mV. Analysis of RNA isolated from these cells by RT-PCR revealed the presence of eight Kv α-subunits (Kvl.1, Kvl.3, Kvl.4, Kv2.2, Kv4.1, Kv4.2, Kv4.3, and Kv9.3), three β-subunits (Kvβl.1, Kvβ2.1, and Kvβ3.1), and two K[sup +] channel interacting protein (KChIP) isoforms (KChIP2 and KChIP3). Western blot analysis with available Kv α-subunit antibodies (Kvl.1, Kvl.3, Kvl.4, Kv4.2, and Kv4.3) showed labeling of 50-kDa proteins from alveolar epithelial cells grown in monolayer culture. Immunocytochemical analysis of cells from monolayers showed that Kvl.1, Kvl.3, Kvl.4, Kv4.2, and Kv4.3 were localized to the apical membrane. We conclude that expression of multiple Kv α-, β-, and KChIP subunits explains the variability in inactivation gating and K[sup +] selectivity observed between cells and that Kv channels in the apical membrane may contribute to basal K[sup +] secretion across the alveolar epithelium. [ABSTRACT FROM AUTHOR]

Investigates the amino acid specificity of Na-dependent amino acid cotransport system that contributes to transepithelial Na absorption in the apical membrane of cultured adult rat alveolar epithelial cell monolayers. More current produced by amino acids with low affinity for the cotransporter; Effects of classes of amino acids on insensitive short-circuit current.

Investigates mechanisms of keratinocyte growth factor-mediated amelioration of lung injury in the peri-bone marrow transplant period. Idiopathic pneumonia syndrome; Keratinocyte growth factor treatment and conditioning schedule for bone marrow transplant experiments; Attenuation of B7 and cytolytic molecule, granzyme B, expression.