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Lucie Parent Stéphane Supplisson Donald D. F. Loo Ernest M. Wright 《The Journal of membrane biology》1992,125(1):49-62
Summary Cystic fibrosis (CF) is characterized by abnormal epithelial Cl– conductance (GCl). In vitro studies that have shown that cAMP regulation is an intrinsic property of the CF-affected GCl(CF-GCl) have been carried out previously on cultured secretory cells and on nonepithelial cells. Even though GCl in absorption is defective in CF, a clear demonstration of cAMP regulation of CF-GCl in a purely absorptive tissue is lacking. We studied the cAMP regulation of CF-GCl in the microperfused intact human reabsorptive sweat duct. About 40% of the ducts responded to cAMP (responsive) while the remainder of the ducts did not. In responsive ducts, cAMP-elevating agents: -adrenergic agonist isoproterenol (IPR), CPT-cAMP, forskolin, theophylline or IBMX increased G
tby about 2.3-fold (n = no. of ducts = 8). Removal of media Cl–, but not amiloride pretreatment (in the lumen), abolished the cAMP response, indicating exclusive activation of GCl. cAMP activated both apical and basolateral GCl. cAMP hyperpolarized gluconate: Cl– (lumen: bath) transepithelial bionic potentials (V
t=–20.3±5.2 mV, mean ±se, n=9) and transepithelial 3 1 luminal NaCl dilution diffusion potentials (V
t=–8.8±2.9 mV, n=5). cAMP activated basolateral GCl as indicated by increased bi-ionic (gluconate: Cl–, bath: lumen) diffusion potentials (by about 12 mV). The voltage divider ratio in symmetric NaCl solutions increased by 60%. Compared to responsive ducts, nonresponsive ducts were characterized by smaller spontaneous transepithelial potentials in symmetrical Ringer's solution (V
t=–6.9±0.8 mV, n=24, nonresponsive vs. –19.4±1.8 mV, n=22, responsive ducts) but larger bi-ionic potentials (–94±6 mV, n=35, nonresponsive vs. –65±5 mV, n=17, responsive ducts) and dilution diffusion potentials (–40±5 mV, n=11, nonresponsive vs. –29±3 mV, n=7, responsive ducts). These results are consistent with an inherently (prestimulus) maximal activation of GCl in nonresponsive ducts and submaximal activation of GCl in responsive ducts. We conclude that cAMP activates CF-G
Cl which is expressed and abnormal in both apical and basal membranes of this absorptive epithelium in CF.Abbreviations CF
cystic fibrosis
-
G
t
transepithelial conductance
-
V
b
electrical potential across the basolateral membrane
-
V
a
electrical potential across the apical membrane
-
V
t
transepithelial potential
- V
b
transepithelial currentinduced voltage deflections across the basolateral membrane
- V
a
transepithelial current-induced voltage deflections across the apical membrane
- V
t
transepithelial current-induced voltage deflection across the epithelium
- VDR
voltage divider ratio
- GCl
transepithelial Cl– conductance
- CF-GCl
cystic fibrosis-affected Cl– conductance
- EMF
electromotive force
- IPR
isoproterenol
- IBMX
3-isobutyl-1-methylxanthine
- CPT-cAMP
chlorophenylthio-adenosine 3-5 cyclic monophosphate
- PGE2
prostaglandin E2 相似文献
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Jan Benes Hana Tomankova Martina Novakova Zdeněk Rohan Richard Kvetnansky Jaromir Myslivecek 《Cellular and molecular neurobiology》2013,33(4):503-511
Glucocorticoids act via glucocorticoid receptors (GR), typically localized in the cytosol (cGR). Rapid action is probably mediated via membrane receptors (mGR). In corticotropin-releasing hormone knockouts (CRH-KO), basal plasma glucocorticoid levels do differ from wild type levels (WT), but are approximately ten times lower during exposure to immobilization stress (IMMO) in comparison to WT. We tested the following hypotheses: (1) the mice lung tissue GR basal numbers would not be changed in CRH-KO (because of similar glucocorticoid levels), (2) the number of GR would be changed in WT but not in KO during short (30, 90, and 120 min) IMMO (because of higher increase of glucocorticoid levels in WT). The basal levels of cGR were not changed in CRH-KO (compared to WT), while mGR were significantly lower (62 %) in CRH-KO. In WT, there was the only decrease (to 32 %) in cGR after 120 min when we also found an increase in mGR in WT (to 201 %). In CRH-KO, IMMO caused gradual decrease in cGR (to 52 % after 30 min, to 46 % after 90 min, and to 32 % after 120 min). In CRH-KO, the only increase in mGR appeared already at 30 min of IMMO. These data suggest, on the contrary to our hypotheses, that CRH-KO are more susceptible to GR changes in early phases of stress. 相似文献
16.
Ouimette Andrew P. Ollinger Scott V. Lepine Lucie C. Stephens Ryan B. Rowe Rebecca J. Vadeboncoeur Matthew A. Tumber-Davila Shersingh J. Hobbie Erik A. 《Ecosystems》2020,23(4):715-729
Ecosystems - Carbon (C) fluxes among different components of plant growth are important to forest ecosystem C cycling and are strongly influenced by species composition and resource availability.... 相似文献
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Ondřej Korábek Lucie Juřičková Adam Petrusek 《Journal of Zoological Systematics and Evolutionary Research》2020,58(4):944-956
Exact locations of glacial refugia are relevant for the study of contemporary biodiversity, not only as places less disturbed during the climatic changes but also as sources of rapid expansion of the biota after the Last Glacial cycle. If continuously inhabited over several of the Quaternary glacial cycles, the refugia are readily identifiable by the accumulated genetic diversity. However, the sources of the Holocene range expansion, particularly important for the emergence of present-day bio- and phylogeographic patterns and for realistic estimation of species’ expansion rates, might have been located at the fringes of the glacial species ranges and lack unique lineages. This problem is pertinent when the variation is explored at slowly evolving genetic markers. We suggest that the location of such source refugia may be approximated by reconstructing the geographic location as a continuous trait evolving along the branches of a phylogenetic tree. We applied this approach, using the BEAST software, on two large southeast European land snail species: Caucasotachea vindobonensis and Helix thessalica. We found evidence for C. vindobonensis refugia in the western Balkans; notable is an apparently old refugium in Bosnia and Herzegovina. The plausible sources of the species’ Holocene range expansion, however, were located around the south-western end of the Carpathians. Although the source areas were likely similar in H. thessalica, some expansion sources suggested by the analyses (e.g., Podolia, Ukraine) appeared implausible and driven by sampling clustered in that area. The applied approach allows for additional exploitation of the mitochondrial data gathered during the past two decades of animal phylogeography studies. 相似文献
19.
Caroline Birer Corrie S. Moreau Niklas Tysklind Lucie Zinger Christophe Duplais 《Molecular ecology》2020,29(7):1372-1385
Bacteria living on the cuticle of ants are generally studied for their protective role against pathogens, especially in the clade of fungus‐growing ants. However, little is known regarding the diversity of cuticular bacteria in other ant host species, as well as the mechanisms leading to the composition of these communities. Here, we used 16S rRNA gene amplicon sequencing to study the influence of host species, species interactions and the pool of bacteria from the environment on the assembly of cuticular bacterial communities on two phylogenetically distant Amazonian ant species that frequently nest together inside the roots system of epiphytic plants, Camponotus femoratus and Crematogaster levior. Our results show that (a) the vast majority of the bacterial community on the cuticle is shared with the nest, suggesting that most bacteria on the cuticle are acquired through environmental acquisition, (b) 5.2% and 2.0% of operational taxonomic units (OTUs) are respectively specific to Ca. femoratus and Cr. levior, probably representing their respective core cuticular bacterial community, and (c) 3.6% of OTUs are shared between the two ant species. Additionally, mass spectrometry metabolomics analysis of metabolites on the cuticle of ants, which excludes the detection of cuticular hydrocarbons produced by the host, were conducted to evaluate correlations among bacterial OTUs and m/z ion mass. Although some positive and negative correlations are found, the cuticular chemical composition was weakly species‐specific, suggesting that cuticular bacterial communities are prominently environmentally acquired. Overall, our results suggest the environment is the dominant source of bacteria found on the cuticle of ants. 相似文献
20.
Ptáková Michaela Pokorný Petr Šída Petr Novák Jan Horáček Ivan Juřičková Lucie Meduna Petr Bezděk Aleš Myšková Eva Walls Matthew Poschlod Peter 《Vegetation History and Archaeobotany》2021,30(2):269-286
Vegetation History and Archaeobotany - In a continuous, perfectly stratified sedimentary sequence which was discovered under a large sandstone overhang in northern Bohemia, Czech Republic, we... 相似文献