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Biomedical subjects

F Lang

Publications and source records attributed to F Lang.

At least 55 records · Page 3Linked to original sources
PubMed2002

Stimulation of TNF alpha expression by hyperosmotic stress.

Hyperosmotic stress is known to induce apoptotic cell death, an effect previously attributed to seemingly ligand-independent clustering of tumour necrosis factor alpha (TNF alpha) receptors. An alternative explanation for the clustering of TNF alpha receptors may be stimulation of TNF alpha production, with subsequent autocrine or paracrine stimulation of the receptors. The present study was performed to test for an effect of exposure to hyperosmotic extracellular fluid on cellular TNF alpha production. In both the macrophage cell line U937 and the B lymphocyte cell line LCL721, an increase of extracellular osmolarity to 500 mosmol/l indeed increased TNF alpha expression, an effect reversed by the p38 kinase inhibitor SB203580. In both cell types hyperosmotic stress triggered apoptosis, which in U937 cells was significantly inhibited by neutralizing antibodies against TNF alpha and by SB203580 and was similarly elicited by exogenous addition of TNF alpha. In contrast, osmotically induced apoptosis of LCL721 cells was only slightly blunted by anti-TNF alpha antibodies and rather increased by SB203580. In conclusion, through activation of p38 kinase hyperosmotic stress stimulates the expression of TNF alpha which at least in U937 macrophages may participate in the triggering of subsequent apoptotic cell death. However, the observations in LCL721 cells point to other, TNF alpha-independent, mechanisms mediating apoptotic cell death following an excessive increase of extracellular osmolarity.

Apoptosis↗
PubMed2002

Hypercorticism blunts circadian variations of osteocalcin regardless of nutritional status.

Anorexia nervosa (AN) and Cushing's syndrome (CS) are both responsible for osteoporosis. The mechanisms leading to osteoporosis in AN include hypogonadism, nutritional depletion, and in some cases hypercorticism. Osteocalcin circulating level is a serum marker of osteoblastic activity that follows a circadian rhythm (OCR). Serum osteocalcin is decreased in both CS and AN and can be increased with treatment. In this study we analyzed the influence of combined cortisol and nutritional status on osteocalcin levels and its circadian rhythm in these two different models of hypercorticism, one nutritionally replete (CS) and one nutritionally deplete (AN), and we evaluated the effects of their treatment (surgical cure and weight gain, respectively). Before treatment, osteocalcin levels were lower in CS (n = 16) and AN (n = 42) than in controls and in the AN patient subgroup with hypercorticism (n = 13) compared to those without (n = 29). OCR was absent in CS and in AN patients with hypercorticism, whereas their circadian cortisol cycle was maintained. In CS, successful surgical treatment increased osteocalcin levels (n = 5) and restored OCR. In AN, weight gain (n = 13) induced a significant decrease in cortisol levels in hypercortisolic AN patients, and restored normal osteocalcin levels and OCR. In conclusion, we found that hypercorticism was associated with a decrease in osteocalcin levels in nutritionally replete or deplete patients and that OCR was more affected by cortisol levels than by cortisol cycle.

Adrenocortical Hyperfunction↗
PubMed2002

Intimal plaque development and oxidative stress in cholesterol-induced atherosclerosis in New Zealand rabbits.

Although oxidative stress is well known in atherogenesis, the origin, nature and kinetics of free radicals involved have not been well described till now. Here, we correlated parameters of oxidative stress with cellular components during induction and stabilization of aortic intimal lesions which were induced in rabbits by feeding a cholesterol-enriched diet for 6 weeks and a normal diet for further 68 weeks. Plasma lipids, aortic plaque size and composition (macrophages, smooth muscle cells, oxidized LDL by morphometry), as well as aortic radical production (by luminol-enhanced chemiluminescence and TEMPO-9AC fluorescence) were measured after various time points. The parameters of oxidative stress were correlated with the different cellular components of the aortic plaques. The plaques increased until week 21, no significant regression was found until week 74, plasma cholesterol was maximal at week 6. Macrophages, oxidized LDL and generation of different species of free radicals were increased during plaque development, yet with different time kinetics. Whereas chemiluminescence correlated only weakly with the amount of intimal macrophages, strong correlations were found between TEMPO fluorescence and smooth muscle cells (r = 0.4778, P < 0.001) and between macrophages and oxidized LDL (r = 0.5896, P < 0.0001). Different indicators of oxidative stress were increased during plaque progression and stabilization. However, the various correlations show, that distinct types of reactive species secreted probably from macrophages and smooth muscle cells contribute to oxidative stress in the different phases of plaque development.

Animals↗
PubMed2002

Up-regulation of the human serum and glucocorticoid-dependent kinase 1 in glomerulonephritis.

Glomerulonephritis is paralleled by excessive formation of transforming growth factor-beta (TGF-beta), which participates in the pathophysiology of the disease. Recently, a novel downstream target of TGF-beta has been identified, i.e. the human serum and glucocorticoid-dependent kinase 1 (hSGK1), a serine/threonine kinase participating in the regulation of Na(+) transport. The present study was performed to elucidate transcriptional regulation of hSGK1 in glomerulonephritis. To this end, in situ hybridization was performed in biopsies from patients with clinical diagnosis of glomerulonephritis. hSGK1 transcript levels were moderately enhanced in 5 out of 9 patients and strongly enhanced in 4 out of 9 patients. Distal nephron epithelial cell hSGK1 transcript levels were low or absent in 7 of the 9 patients but markedly enhanced in 2 of the 9 patients. In conclusion, glomerulonephritis leads to glomerular and in some cases to epithelial up-regulation of hSGK1 transcription.

Adult↗
PubMed2002

Analysis of the genes SLC7A9 and SLC3A1 in unclassified cystinurics: mutation detection rates and association between variants in SLC7A9 and the disease.

Cystinuria is a common inherited disorder of defective renal reabsorption of cystine and dibasic amino acids. Recently, 2 responsible genes have been identified: mutations in the SLC3AI gene encoding the glycoprotein rBAT cause cystinuria type I, while variants in the SLC7A9 gene have been demonstrated in non-type I cystinuria; its gene product b(0)+AT is the light chain of the renal cystine transport system rBAT/b(0),+-AT. To estimate the role of both genes in the etiology of cystinuria, we searched for sequence alterations in SLC7A9 and SLC3AI: 30 unclassified cystinurics were investigated. In 50% of patients (15/30), point mutations in SLC3A1 were detected. Screening of the SLC7A9 gene revealed 10 mutations in 8 patients corresponding to a frequency of 27%. In addition to previously published mutations in the SLC7A9 gene, we detected 2 new mutations (F 140S, c747delG). An overall detection rate of 73% (22/30) in unclassified patients is delineated for mutations in both genes. In 33% (10/30), 2 mutations were detected, in 40% (12/30) 1 mutation. Furthermore, 5 new polymorphic sites were identified in SLC7A9. While the base pair variation in intron 9 is homogeneously distributed in patients and control individuals, the allelic and genotypic distributions of the polymorphisms in 3 exons of SLC7A9--exons 2, 5 and 6--and intron 3 differ significantly between both groups. Our results suggest that some haplotypes defined through the exons 2, 5 and 6 and intron 3 might be markers of a functional variant in the SLC7A9 gene. Evidently, since the mutation detection rates in the 2 so far known cystinuria genes never reach 100%, further genes and modulating factors should influence the phenotype in a subset of patients. However, the presented data show that testing for mutations in the 2 currently known cystinuria genes is already a meaningful approach to the molecular diagnostics of the disease.

Amino Acid Transport Systems, Basic↗
PubMed2001

IGF-1 up-regulates K+ channels via PI3-kinase, PDK1 and SGK1.

Involvement of voltage-gated (Kv) potassium channels in IGF-1-induced proliferation of HEK293 cells was studied by patch-clamp, RT-PCR and FACS analysis. IGF-1 up-regulated outwardly rectifying whole-cell K+ current starting after 1 h of incubation and reaching a maximum after 4-6 h. The IGF-1-stimulated current was voltage-gated with an activation threshold of -30 mV to -40 mV, a half-maximal activation at +5.3+/-1.8 mV, and time constants for activation and inactivation of 4.5+/-0.4 ms and 43.5+/-5.6 ms ( n=10), respectively. The current was inhibited by TEA, margatoxin, agitoxin-2 and stichodactyla toxin. PCR amplification of different Kv subunits from HEK293 cDNA demonstrated the expression of Kv1.1, Kv1.2, Kv1.3, Kv1.4, Kv3.1 and Kv3.4 mRNA. Quantitative RT-PCR showed up-regulation of Kv1.1, 1.2 and 1.3 mRNA by IGF-1. The effect of IGF-1 on K+ current was blocked by inhibitors of phosphatidylinositol 3-kinase (PI3-kinase), wortmannin and LY294002, and mimicked by overexpression of human 3-phosphoinositide-dependent protein kinase-1 (hPDK1) or serum- and glucocorticoid-dependent kinase-1 (hSGK1), both sequential downstream targets of PI3-kinase. IGF-1-induced proliferation of HEK293 cells was inhibited by both K+ channel blockers and inhibitors of PI3-kinase. In conclusion, IGF-1 through PI3-kinase, PDK1 and SGK1 up-regulates Kv channels, an effect required for the proliferative action of the growth factor.

3-Phosphoinositide-Dependent Protein Kinases↗
PubMed2001

Regulation and physiological roles of serum- and glucocorticoid-induced protein kinase isoforms.

Serum- and glucocorticoid-induced protein kinase 1 (SGK1) was identified in 1993 as an immediate early gene whose mRNA levels increase dramatically within 30 minutes when cells are exposed to serum or glucocorticoids, or both. Subsequently, many other agonists, acting through a variety of signal transduction pathways, have been shown to induce SGK1 gene transcription in cells and tissues. SGK1 is a member of the "AGC" subfamily, which includes protein kinases A, G, and C, and its catalytic domain is most similar to protein kinase B (PKB). Like PKB, SGK1 is activated by phosphorylation in response to signals that stimulate phosphatidylinositol 3-kinase, and this is mediated by 3-phosphoinositide-dependent protein kinase 1 (PDK1) and another protein kinase that has yet to be identified. Thus, SGK1 is remarkable in being activated at both the transcriptional and posttranslational levels by a huge number of extracellular signals. In contrast, little is known about the transcriptional regulation of the two closely related isoforms SGK2 and SGK3, although they can be activated by phosphorylation. The substrate specificity of SGK isoforms superficially resembles that of PKB in that serine and threonine residues lying in Arg-Xaa-Arg-Xaa-Xaa-Ser/Thr sequences (where Xaa is a variable amino acid) are phosphorylated. However, although they may have some substrates in common, evidence is emerging that SGK1 and PKB phosphorylate distinct proteins and have different functions in vivo. In particular, SGK1 plays an important role in activating certain potassium, sodium, and chloride channels, suggesting an involvement in the regulation of processes such as cell survival, neuronal excitability, and renal sodium excretion. Moreover, sustained high levels of SGK1 protein and activity may contribute to conditions such as hypertension and diabetic nephropathy. This raises the possibility that specific inhibitors of SGK1 may have therapeutic potential for the treatment of several diseases.

Amino Acid Sequence↗
PubMed2001

Cerebral localization and regulation of the cell volume-sensitive serum- and glucocorticoid-dependent kinase SGK1.

The serum- and glucocorticoid-dependent kinase SGK1 is regulated by alterations of cell volume, whereby cell shrinkage increases and cell swelling decreases the transcription, expression and activity of SGK1. The kinase is expressed in all human tissues studied including the brain. The present study was performed to localize the sites of SGK1 transcription in the brain, to elucidate the influence of the hydration status on SGK1 transcription and to explore the functional significance of altered SGK1 expression. Northern blot analysis of human brain showed SGK1 to be expressed in all cerebral structures examined: amygdala, caudate nucleus, corpus callosum, hippocampus, substantia nigra, subthalamic nucleus and thalamus. In situ hybridization and immunohistochemistry in the rat revealed increased expression of SGK1 in neurons of the hippocampal area CA3 after dehydration, compared with similar slices from brains of euvolaemic rats. Additionally, several oligodendrocytes, a few microglial cells, but no astrocytes, were positive for SGK1. The abundance of SGK1 mRNA in the temporal lobe, including hippocampus, was increased by dehydration and SGK1 transcription in neuroblastoma cells was stimulated by an increase of extracellular osmolarity. Co-expression studies in Xenopus laevis oocytes revealed that SGK1 markedly increased the activity of the neuronal K+ channel Kv1.3. As activation of K+ channels modifies excitation of neuronal cells, SGK1 may participate in the regulation of neuronal excitability.

Animals↗
PubMed2001

Synthesis of a muscarinic receptor antagonist via a diastereoselective Michael reaction, selective deoxyfluorination and aromatic metal-halogen exchange reaction.

An efficient synthesis of a structurally unique, novel M(3) antagonist 1 is described. Compound 1 is conveniently disconnected retrosynthetically at the amide bond to reveal the acid portion 2 and the amine fragment 3. The synthesis of key intermediate 2 is highlighted by a ZnCl(2)-MAEP complex 19 catalyzed diastereoselective Michael reaction of dioxolane 7 with 2-cyclopenten-1-one (5) to establish the contiguous quaternary-tertiary chiral centers and a subsequent geminal difluorination of ketone 17 using Deoxofluor in the presence of catalytic BF(3).OEt(2). The synthesis of the amine moiety 3 is highlighted by the discovery of a novel n-Bu(3)MgLi magnesium-halogen exchange reaction for selective functionalization of 2,6-dibromopyridine. This new and practical metalation protocol obviated cryogenic conditions and upon quenching with DMF gave 6-bromo-2-formylpyridine (26) in excellent yield. Further transformations afforded the amine fragment 3 via reductive amination with 35, Pd-catalyzed aromatic amination, and deprotection. Finally, the highly convergent synthesis of 1 was accomplished by coupling of the two fragments. This synthesis has been used to prepare multi-kilogram quantities of the bulk drug.

Amides↗
PubMed2001

Human acid ceramidase: processing, glycosylation, and lysosomal targeting.

The biosynthesis of human acid ceramidase (hAC) starts with the expression of a single precursor polypeptide of approximately 53-55 kDa, which is subsequently processed to the mature, heterodimeric enzyme (40 + 13 kDa) in the endosomes/lysosomes. Secretion of hAC by either fibroblasts or acid ceramidase cDNA-transfected COS cells is extraordinarily low. Both lysosomal targeting and endocytosis critically depend on a functional mannose 6-phosphate receptor as judged by the following criteria: (i) hAC-precursor secretion by NH(4)Cl-treated fibroblasts and I-cell disease fibroblasts, (ii) inhibition of the formation of mature heterodimeric hAC in NH(4)Cl-treated fibroblasts or in I-cell disease fibroblasts, and (iii) blocked endocytosis of hAC precursor by mannose 6-phosphate receptor-deficient fibroblasts or the addition of mannose 6-phosphate. The influence of the six individual potential N-glycosylation sites of human acid ceramidase on targeting, processing, and catalytic activity was determined by site-directed mutagenesis. Five glycosylation sites (sites 1-5 from the N terminus) are used. The elimination of sites 2, 4, and 6 has no influence on lysosomal processing or enzymatic activity of recombinant ceramidase. The removal of sites 1, 3, and 5 inhibits the formation of the heterodimeric enzyme form. None of the mutant ceramidases gave rise to an increased rate of secretion, suggesting that lysosomal targeting does not depend on one single carbohydrate chain.

Ammonium Chloride↗
PubMed2001

Association of 4F2hc with light chains LAT1, LAT2 or y+LAT2 requires different domains.

Heterodimeric amino acid transporters are comprised of a type-II membrane protein named the heavy chain (4F2hc or rBAT) that may associate with a number of different polytopic membrane proteins, called light chains. It is thought that the heavy chain is mainly involved in the trafficking of the complex to the plasma membrane, whereas the transport process itself is catalysed by the light chain. The 4F2 heavy chain (4F2hc) associates with at least six different light chains to induce distinct amino acid-transport activites. To test if the light chains are specifically recognized and to identify domains involved in the recognition of light chains, C-terminally truncated mutants of 4F2hc were constructed and co-expressed with the light chains LAT1, LAT2 and y(+)LAT2. The truncated isoform T1, comprised of only 133 amino acids that form the cytosolic N-terminus and the transmembrane helix, displayed only a slight reduction in its ability to promote LAT1 expression at the membrane surface compared with the 529 amino acid wild-type 4F2hc protein. Co-expression of increasingly larger 4F2hc mutants caused a delayed translocation of LAT1. In contrast to the weak effects of 4F2hc truncations on LAT1 expression, surface expression of LAT2 and y(+)LAT2 was almost completely lost with all truncated heavy chains. Co-expression of LAT1 together with the other light chains did not result in displacement of LAT2 and y(+)LAT2. The results suggest that extracellular domains of the heavy chain are responsible mainly for recognition of light chains other than LAT1 and that the extracellular domain ensures proper translocation to the plasma membrane.

Amino Acid Transport Systems↗
PubMed2001

Cloning and characterization of SLC26A6, a novel member of the solute carrier 26 gene family.

The SLC26 gene family (solute carrier family 26) comprises five mammalian genes that encode anion transporter-related proteins. In addition to sat-1 and prestin, which were cloned from rat and gerbil, respectively, three human members have been identified and associated with specific genetic diseases (DTD, diastrophic dysplasia; CLD, congenital chloride diarrhea; PDS, Pendred syndrome). In this study we used a homology approach combined with RACE PCR to identify human SLC26A6, the sixth member of this gene family. Northern blot analysis showed the highest SLC26A6 transcript levels in kidney and pancreas. Expression in MDCK cells and in Xenopus oocytes demonstrated trafficking of the SLC26A6 protein to the cell membrane but did not reveal anion transport activity with tracer uptake or intracellular pH measurements. We determined the genomic structure of the SLC26A6 gene and excluded mutations in the 21 coding exons as the cause of DFNB6 and USH2B, which closely map to the SLC26A6 chromosomal locus (3p21).

Amino Acid Sequence↗
PubMed2001

Treatment of advanced breast cancer with vinorelbine and docetaxel with or without human granulocyte colony-stimulating factor.

PURPOSE: A multicenter phase II trial was performed to investigate the efficacy and tolerance of docetaxel, vinorelbine with or without recombinant human granulocyte colony-stimulating factor (G-CSF) in patients with metastatic breast cancer. PATIENTS AND METHODS: Between February 1998 and March 1999, 57 patients participated in this trial. Forty-two patients received this combination as first-line and 15 patients as second-line chemotherapy, including 10 patients who had failed anthracyclines. Therapy consisted of vinorelbine 30 mg/m(2) on days 1 and 15 and docetaxel 30 mg/m(2) on days 1, 8, and 15 every 4 weeks. Depending on the absolute neutrophil counts on the day of scheduled chemotherapeutic drug administration, a 5-day course of G-CSF 5 microg/kg/d was given. RESULTS: The overall response rate was 64.3% (95% confidence interval, 48.1% to 78.4%) in patients receiving docetaxel plus vinorelbine as first-line chemotherapy, including eight complete (19%) and 19 partial remissions (45.3%); 11 patients (26.2%) had disease stabilization, and only four (9.5%) progressed. Second-line treatment with this regimen resulted in eight (53.3%) of 15 objective responses, four had stable disease, and three had progressive disease. The median time to progression was 12 months in the first-line and 9.8 months in the second-line setting, respectively. After a median follow-up time of 18 months, 38 patients (65%) were still alive with metastatic disease. Myelosuppression was commonly observed; World Health Organization grade 3 or 4 neutropenia both occurred in 18 patients (32%) and was complicated by septicemia in four cases; grade 3 or 4 thrombocytopenia was seen in two patients (4%), and grade 3 anemia was seen in only one patient (2%). Severe (grade 3) nonhematologic toxicity, except for alopecia, was rarely observed and included nausea/vomiting in two patients (4%), and stomatitis, peripheral neuropathy, and skin toxicity each in one patient. CONCLUSION: Our data suggest that docetaxel and vinorelbine with or without G-CSF is an effective and fairly well tolerated regimen for the treatment of advanced breast cancer. It might be particularly useful in patients previously exposed to adjuvant or palliative anthracyclines and/or alkylating agents.

Adult↗
PubMed2001

Frequent recognition of BCRF1, a late lytic cycle protein of Epstein-Barr virus, in the HLA-B*2705 context: evidence for a TAP-independent processing.

Using a transient COS transfection assay, allowing a rapid estimation of the dominant CD8(+) T cell responses against a large number of HLA/viral protein combinations within polyclonal cell lines, we searched for HLA-B*2705-restricted CD8 T cell responses to Epstein-Barr virus (EBV) within T cell samples enriched for EBV-reactive cells. Among the 18 EBV proteins tested, only 2, the latent protein EBNA3A and the late lytic protein BCRF1 (viral IL-10), appeared dominant in the B27 context, as they triggered significant TNF and cytolytic responses in some donors. We provide evidence that the B27/BCRF1 epitope (RRLVVTLQC) is located in the signal sequence and that it can be presented in a TAP-independent manner. Using B27/BCRF1 monomeric complexes coated on immunomagnetic beads, we sorted out BCRF1-specific CD8 T cells from 8 of 15 HLA-B27(+) donors. This is, to our knowledge, the first demonstration of a recognition of BCRF1, suggesting that some immune control against EBV exists even during the late stage of the lytic cycle. This result also strengthens the unusual ability of HLA-B*2705 to present peptide in a TAP-independent manner.

Animals↗
PubMed2001

Protein and mRNA expression of serum and glucocorticoid-dependent kinase 1 in metanephrogenesis.

Abstract Expression of serum and glucocorticoid-dependent kinase 1 (SGK1) during development in mouse kidney (embryonic day [E] 14 to postnatal day [P] 1) was studied by in situ hybridization and immunofluorescence. In whole embryos, SGK1 mRNA was highly abundant in the developing metanephros, where SGK1 mRNA was expressed in the ureteric buds of the branching collecting duct system and in the mesenchymal blastema-derived comma- and s-shaped bodies. In E14 kidneys, SGK1 protein was below detection level, whereas at day E16, ureteric buds, s-shaped bodies and outgrowing loops of Henle expressed detectable amounts of SGK1 protein. SGK1 protein was also expressed in E16 primary tubules of the collecting duct system. In P1 kidneys, no or only faint SGK1 protein expression was apparent in comma- and s-shaped bodies, whereas SGK1 was continuously expressed by medullary collecting ducts. In conclusion, SGK1 is developmentally expressed in metanephrogenesis. High expression in developing collecting duct and in blastema-derived comma- and s-shaped bodies suggests a dual function of SGK1 in maturation of the reabsorbing collecting duct epithelium and in epithelial transition of the blastema cells.

Animals↗
PubMed2001

2D and 3D CT imaging correlated to rigid endoscopy in complex laryngo-tracheal stenoses.

The aim of this study was to compare 2D and 3D CT imaging in the pre- and postoperative evaluation of complex benign larynges-tracheal airway stenoses with rigid endoscopy, considered as the gold standard. Six patients (aged 5-72 years) with a total of nine complex laryngo-tracheal stenoses underwent non-contrast helical CT scans (slice thickness 3 mm, pitch 1.3, reconstruction interval 1.5 mm) before and after surgical resection. With prototype software, virtual endoscopy (VE) post-processing algorithms were applied to the imaging data sets. The VE and multiplanar 2D findings were compared with rigid endoscopy, considered as standard of reference. All nine stenoses were correctly identified on 3D images and their anatomical locations correctly assessed on 2D reconstructions. Artifacts were met when patients were unable to suspend their breath, leading to one false-positive result. Two-dimensional images and 3D VE of tracheal stenoses proved to be efficient and complementary to the rigid endoscopy, permitting a reliable endoluminal 3D view and evaluation of the surrounding anatomical structures. Limitations of this technique relate to the maximal spatial resolution of 1.5 mm, the lack of color, and the inability to assess the mucosa. Virtual endoscopy is for complex laryngo-tracheal stenoses an excellent complement for rigid endoscopy, remaining the method of reference, and may be indicated with complicated pathological structures.

Adolescent↗
PubMed2001

Chloride conductance and volume-regulatory nonselective cation conductance in human red blood cell ghosts.

To identify the ion channels involved in erythrocyte volume regulation, whole-cell currents from human red blood cells (RBCs) were recorded in isotonic, hypotonic and hypertonic media. In isotonic NaCl bath solution, whole-cell currents rectified outwardly with reversal potentials (Vrev) between the equilibrium potential of Cl- (ECl) and that of nonselective cations (NSC), ENSC. Replacement of bath Cl by gluconate decreased outward conductance (G outward) by 43 +/- 6% (n = 5) and shifted Vrev with ECl indicating a high fractional Cl- conductance. Hypotonic cell swelling reversibly decreased G outward by 23 +/- 3% (n = 8) while hypertonic cell shrinkage reversibly increased G outward by 27 +/- 8% (n = 5). These shrinkage-activated and swelling-inactivated current fractions rectified outwardly with Vrev at ENSC suggesting that both fractions are generated by the same type of NSC channel. The shrinkage-activated deltaG outward decreased from 4.7 +/- 1.2 nS (n = 3) to 1.4 +/- 0.4 nS (n = 5) and 0.5 +/- 0.4 nS (n = 7) with the increase of pipette [Cl-] from 7 mM to 39 mM and 139 mM, respectively. Similarly, with this increase of pipette [Cl-], G outward under isotonic control conditions decreased from 8.2 +/- 1.4 nS (n = 5) to 7.4 +/- 1.0 nS (n = 20) and 4.1 +/- 0.7 nS (n = 17), due to the differing activity of these NSC channels. In conclusion, human RBCs express, besides a high fractional Cl- conductance, NSC channels that are regulated by cell volume and the cytosolic [Cl-].

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗