scholarly journals Increase in Tetrahydrobiopterin Release from PC 12 Cells under Hypotonic Culture Conditions is Inhibited by HgCl2

Pteridines ◽  
2005 ◽  
Vol 16 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Nobuo Nakanishi ◽  
Kinji Kurihara ◽  
Akito Tomomura ◽  
Keiichi Tonosaki ◽  
Yoshiyuki Hattori ◽  
...  
Keyword(s):  
Choline Chloride ◽  
Water Channel ◽  
Extracellular Fluid ◽  
Culture Conditions ◽  
Hypotonic Medium ◽  
Sodium Glutamate ◽  
Pc 12 Cells ◽  
Water Influx ◽  
Nacl Concentration ◽  
A Site

Abstract Tetrahydrobiopterin (BH4) was released from PC 12 cells to the extracellular fluid. We found that the BH4 outward flow from the cells placed in Hanks medium was increased when NaCl concentration of the medium was decreased. Increase in the BH4 out flow was not observed when NaCl in the Hanks medium was substituted with sodium glutamate (0.14 M), choline chloride (0.14 M) or sucrosc (0.25 M). HgCl2, an inhibitor of water channel, aquaporin, prevented the increase in BH4 out flow caused by the hypotonic medium. The results suggested the presence of a site in BH4 transport which was stimulated by osmotic pressure and/or water influx.

Ca2+-dependent desensitization of insulin secretion by strong potassium depolarization

2012 ◽  
Vol 303 (2) ◽  
pp. E223-E233 ◽  
Author(s):  
M. Willenborg ◽  
M. Belz ◽  
K. Schumacher ◽  
A. Paufler ◽  
K. Hatlapatka ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Glucose Concentration ◽  
Choline Chloride ◽  
Inhibitory Effect ◽  
High K ◽  
Nacl Concentration ◽  
Voltage Dependent ◽  
Fast Decline ◽  
Insulinotropic Effect ◽  
Initial Peak

Depolarization by a high K+ concentration is a widely used experimental tool to stimulate insulin secretion. The effects occurring after the initial rise in secretion were investigated here. After the initial peak a fast decline occurred, which was followed by a slowly progressive decrease in secretion when a strong K+ depolarization was used. At 40 mM KCl, but not at lower concentrations, the decrease continued when the glucose concentration was raised from 5 to 10 mM, suggesting an inhibitory effect of the K+ depolarization. When tolbutamide was added instead of the glucose concentration being raised, a complete inhibition down to prestimulatory values was observed. Equimolar reduction of the NaCl concentration to preserve isoosmolarity enabled an increase in secretion in response to glucose. Unexpectedly, the same was true when the Na+-reduced media were made hyperosmolar by choline chloride or mannitol. The insulinotropic effect of tolbutamide was not rescued by the compensatory reduction of NaCl, suggesting a requirement for activated energy metabolism. These inhibitory effects could not be explained by a lack of depolarizing strength or by a diminished free cytosolic Ca2+ concentration ([Ca2+]i). Rather, the complexation of extracellular Ca2+ concomitant with the K+ depolarization markedly diminished [Ca2+]i and attenuated the inhibitory action of 40 mM KCl. This suggests that a strong but not a moderate depolarization by K+ induces a [Ca2+]i-dependent, slowly progressive desensitization of the secretory machinery. In contrast, the decline immediately following the initial peak of secretion may result from the inactivation of voltage-dependent Ca2+ channels.

Release of dopamine and norepinephrine by hypoxia from PC-12 cells

1998 ◽  
Vol 274 (6) ◽  
pp. C1592-C1600 ◽  
Author(s):  
Ganesh K. Kumar ◽  
Jeffrey L. Overholt ◽  
Gary R. Bright ◽  
Kwong Y. Hui ◽  
Hongwen Lu ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Kinase Inhibitors ◽  
Culture Conditions ◽  
Protein Kinase Inhibitors ◽  
Channel Blockers ◽  
Pc 12 Cells ◽  
Stimulus Secretion Coupling ◽  
Carbon Fiber Electrode ◽  
Da Release

We examined the effects of hypoxia on the release of dopamine (DA) and norepinephrine (NE) from rat pheochromocytoma 12 (PC-12) cells and assessed the involvement of Ca2+ and protein kinases in stimulus-secretion coupling. Catecholamine release was monitored by microvoltammetry using a carbon fiber electrode as well as by HPLC coupled with electrochemical detection (ECD). Microvoltammetric analysis showed that hypoxia-induced catecholamine secretion (Po 2 of medium ∼40 mmHg) occurred within 1 min after the onset of the stimulus and reached a plateau between 10 and 15 min. HPLC-ECD analysis revealed that, at any level of Po 2, the release of NE was greater than the release of DA. In contrast, in response to K+ (80 mM), DA release was ∼11-fold greater than NE release. The magnitude of hypoxia-induced NE and DA releases depended on the passage, source, and culture conditions of the PC-12 cells. Omission of extracellular Ca2+ or addition of voltage-gated Ca2+ channel blockers attenuated hypoxia-induced release of both DA and NE to a similar extent. Protein kinase inhibitors, staurosporine (200 nM) and bisindolylmaleimide I (2 μM), on the other hand, attenuated hypoxia-induced NE release more than DA release. However, protein kinase inhibitors had no significant effect on K+-induced NE and DA releases. These results demonstrate that hypoxia releases catecholamines from PC-12 cells and that, for a given change in Po 2, NE release is greater than DA release. It is suggested that protein kinases are involved in the enhanced release of NE during hypoxia.

scholarly journals Experimental evolution recapitulates natural evolution

2000 ◽  
Vol 355 (1403) ◽  
pp. 1677-1684 ◽  
Author(s):  
H. A. Wichman ◽  
L. A. Scott ◽  
C. D. Yarber ◽  
J. J. Bull
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Experimental Evolution ◽  
Laboratory Culture ◽  
Culture Conditions ◽  
Natural Evolution ◽  
Amino Acid Variation ◽  
Experimental Line ◽  
Amino Acid Levels ◽  
A Site

Genomes of the closely related bacteriophages ϕX174 and S13 are 5386 bases long and differ at 114 nucleotides, affecting 28 amino acids. Both parental phages were adapted to laboratory culture conditions in replicate lineages and analysed for nucleotide changes that accumulated experimentally. Of the 126 experimental substitutions, 90% encoded amino–acid changes, and 62% of the substitutions occurred in parallel in more than one experimental line. Furthermore, missense changes at 12 of the experimental sites were at residues differing between the parental phages; in ten cases the ϕX174 experimental lineages were convergent with the S13 parent, or vice versa, at both the nucleotide and amino–acid levels. Convergence at a site was even obtained in both directions in three cases. These results point to a limited number of pathways taken during evolution in these viruses, and also raise the possibility that much of the amino–acid variation in the natural evolution of these viruses has been selected.

scholarly journals Hydrocarbon-Degrading Bacterial Strain Pseudomonas mendocina Newly Isolated from Marine Sediments and Seawater of Oran Harbor (Algerian Coast)

2020 ◽  
Vol 2 (2) ◽  
pp. 22-29
Author(s):  
Bendadeche Medjahed Faiza
Keyword(s):  
Energy Source ◽  
Growth Rate ◽  
Crude Oil ◽  
16S Rdna ◽  
Marine Sediments ◽  
Growth Kinetic ◽  
Culture Conditions ◽  
Pseudomonas Mendocina ◽  
Degrading Bacterium ◽  
Nacl Concentration

Contamination by petroleum hydrocarbons causes serious dangers to human health and the environment, whether by accidental or chronic contamination. Due to the large flow of ships, the commercial harbor of Oran is subject to pollution particularly by polycyclic aromatic hydrocarbons. For that, bioremediation by indigenous microorganisms is the most important method to eliminate or decrease this contamination. In the present paper, hydrocarbon-degrading bacterium strain SP57N has been studied, newly isolated from contaminated marine sediments and sea water from the harbor of Oran (Northwestern-Algeria), using of Bushnell-Hass salt medium (BHSM). The strain SP57N was Gram-negative, oxidase negative, catalase negative, motile, Rod-shaped bacteria, identified molecularly as Pseudomonas mendocina based on partial 16S rDNA gene sequence analysis, using the BLAST program on National Centre for Biotechnology Information (NCBI) and the EzBioCloud 16S rDNA databases. This isolate could growth on high concentrations of crude oil (up to 10 %, v/v). The effects of some culture conditions such as temperature, NaCl concentration and pH on growth rate of strain SP57N on crude oil as the sole carbon and energy source were studied. In addition, growth kinetic of this isolate on crude oil during 20 days of culture at 140 rpm, under optimal culture conditions was considered. The results showed maximum growth rate at temperature 25°C, 3% (w/v) of NaCl concentration and pH 7. Results of growth kinetic on crude oil as sole carbon and energy source showed that the stationary phase was attained at day 12. Thus, Pseudomonas mendocina SP57N had effectively hydrocarbon-degrading potential, and could be used as an efficacy degrader to initiate a biological eco-friendly method for the bioremediation of the hydrocarbon pollution on the port of Oran, and marine environment.

scholarly journals Isolation of Polyhydroxybutyrate (PHB) Producing Bacteria, Optimization of Culture Conditions for PHB production, Extraction and Characterization of PHB

2019 ◽  
Vol 6 (1) ◽  
pp. 62-68 ◽  
Author(s):  
Christina Thapa ◽  
Pallavi Shakya ◽  
Rabina Shrestha ◽  
Sushovita Pal ◽  
Prakash Manandhar
Keyword(s):  
Culture Condition ◽  
Production Cost ◽  
Micrococcus Luteus ◽  
Culture Conditions ◽  
Bacillus Pasteurii ◽  
Nacl Concentration ◽  
Phb Production ◽  
High Production ◽  
High Production Cost ◽  
Micro Organisms

Polyhydroxybutyrates (PHBs) are energy reserves synthesized by different micro-organisms such as Alcaligenes, Pseudomonas, Staphylococcus, Algae, in excess of carbon and limitation of nutrients like nitrogen. These biopolymers are suitable alternate to synthetic carbon-based polymers. However, the high production cost limits their commercialization. The aim of this study was thus, focused on optimization of culture condition for maximum PHB production in an attempt to reduce the production cost. The micro-organisms for this purpose were isolated from 4 different soil samples and screened for PHB production. Culture conditions for these organisms were optimized by changing the parameters, viz., incubation time, pH, carbon source and NaCl concentration. Thus, optimized culture condition was used to culture the isolates for extraction of PHB and its analysis. The extracted compounds on FTIR-analysis gave characteristic C=O peak of PHB, thus, confirming the seven isolates to be PHB producers. Results for optimized parameters for the isolated PHB positive species showed that synthesis of PHB was maximum at 48 hours i.e. during the early stages of stationary phase. However, different isolates favored different culture conditions. Highest PHB accumulation and growth of isolates were seen at pH 7 and 9. Similarly, it was observed that glucose was favored by 4 isolates and sucrose was favored by 3 isolates. Interestingly, NaCl concentration did not cause significant effect on neither the bacterial growth nor the PHB production. During the extraction of PHB from the optimized culture conditions, extraction of PHB from broth gave significant yield than that from agar. A good PHB yield from broth amounting to 36.41% and 34.59% was observed for Bacillus pasteurii and Micrococcus luteus respectively, showing a potential for their exploitation in industrial PHB production. At optimized conditions, 7 isolates exhibited significant PHB yields, thus showing a potential for further exploitation.

scholarly journals Striking Differences in Glucose and Lactate Levels between Brain Extracellular Fluid and Plasma in Conscious Human Subjects: Effects of Hyperglycemia and Hypoglycemia

2002 ◽  
Vol 22 (3) ◽  
pp. 271-279 ◽  
Author(s):  
Walid M. Abi-Saab ◽  
David G. Maggs ◽  
Tim Jones ◽  
Ralph Jacob ◽  
Vinod Srihari ◽  
...  
Keyword(s):  
Human Subjects ◽  
Intractable Epilepsy ◽  
Extracellular Fluid ◽  
Intracerebral Microdialysis ◽  
Brain Extracellular Fluid ◽  
Lactate Levels ◽  
A Site ◽  
Clamp Study ◽  
The Relationship ◽  
The Brain

Brain levels of glucose and lactate in the extracellular fluid (ECF), which reflects the environment to which neurons are exposed, have never been studied in humans under conditions of varying glycemia. The authors used intracerebral microdialysis in conscious human subjects undergoing electro-physiologic evaluation for medically intractable epilepsy and measured ECF levels of glucose and lactate under basal conditions and during a hyperglycemia–hypoglycemia clamp study. Only measurements from nonepileptogenic areas were included. Under basal conditions, the authors found the metabolic milieu in the brain to be strikingly different from that in the circulation. In contrast to plasma, lactate levels in brain ECF were threefold higher than glucose. Results from complementary studies in rats were consistent with the human data. During the hyperglycemia–hypoglycemia clamp study the relationship between plasma and brain ECF levels of glucose remained similar, but changes in brain ECF glucose lagged approximately 30 minutes behind changes in plasma. The data demonstrate that the brain is exposed to substantially lower levels of glucose and higher levels of lactate than those in plasma; moreover, the brain appears to be a site of significant anaerobic glycolysis, raising the possibility that glucose-derived lactate is an important fuel for the brain.

scholarly journals Epithelial sodium channel (ENaC) in GtoPdb v.2021.2

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Israel Hanukoglu
Keyword(s):  
Epithelial Cells ◽  
Cell Surface ◽  
Respiratory Tract ◽  
Reproductive Tract ◽  
Basolateral Membrane ◽  
Water Channel ◽  
Extracellular Fluid ◽  
Female Reproductive Tract ◽  
Filament Bundles ◽  
Na Ions

The epithelial sodium channels (ENaC) are located on the apical membrane of epithelial cells in the kidney tubules, lung, respiratory tract, male and female reproductive tracts, sweat and salivary glands, placenta, colon, and some other organs [9, 13, 22, 21, 42]. In these epithelia, Na+ ions flow from the extracellular fluid into the cytoplasm of epithelial cells via ENaC. The Na+ ions are then pumped out of the cytoplasm into the interstitial fluid by the Na+/K+ ATPase located on the basolateral membrane [36]. As Na+ is one of the major electrolytes in the extracellular fluid (ECF), osmolarity change initiated by the Na+ flow is accompanied by a flow of water accompanying Na+ ions [6]. Thus, ENaC has a central role in regulating ECF volume and blood pressure, primarily via its function in the kidney [37]. The expression of ENaC subunits, hence its activity, is regulated by the renin-angiotensin-aldosterone system, and other factors involved in electrolyte homeostasis [37, 30]. In the respiratory tract and female reproductive tract, large segments of the epithelia are composed of multi-ciliated cells. In these cells, ENaC is located along the entire length of the cilia that cover the cell surface [15]. Cilial location greatly increases ENaC density per cell surface and allows ENaC to serve as a sensitive regulator of osmolarity of the periciliary fluid throughout the whole depth of the fluid bathing the cilia [15]. In contrast to ENaC, CFTR (ion transporter defective in cystic fibrosis) is located on non-cilial cell-surface [15]. In the vas deferens segment of the male reproductive tract, the luminal surface is covered by microvilli and stereocilia projections with backbones composed of actin filament bundles [42]. In these cells, both ENaC and the water channel aquaporin AQP9 are localized on these projections and also in the basal and smooth muscle layers [42]. Thus, ENaC function is also essential for the clearance of respiratory airways, transport of germ cells, fertilization, implantation, and cell migration [15, 22].

Abstract 250: Endothelial Cell Endothelin (ET-1) Production is Enhanced with Increasing NaCl Concentration.

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Joshua S Speed ◽  
Jennifer S Pollock ◽  
David M Pollock
Keyword(s):  
Endothelial Cells ◽  
Salt Intake ◽  
Vascular Endothelial Cells ◽  
Choline Chloride ◽  
Fold Increase ◽  
Fold Change ◽  
High Salt ◽  
High Salt Intake ◽  
Nacl Concentration ◽  
The Media

It has recently been demonstrated that increasing salt intake results in an accumulation of sodium within the interstitium of the skin of normal rats, which leads to an immune response that is necessary to maintain normal blood pressure. ET-1 mediates increased inflammation in several models of hypertension and is increased in response to high salt intake. However, it is unknown if ET-1 production is increased by endothelial cells in response to increasing NaCl concentration. Therefore, we hypothesized that increasing the media NaCl concentration will lead to an increase in ET-1 production by human umbilical venous endothelial cells (HUVECs). Exposure of HUVECs for 2 hours to a 40 mosm increase in NaCl results in a significant increase in ET-1 mRNA (1.65±0.14 fold increase vs. control; n=3, p<0.05). This increase in Na+ concentration is similar to that observed in the interstitium of the skin of rats placed on a high NaCl diet. Furthermore, exposure to +40 mosm of mannitol, an effective osmolyte, or urea, an ineffective osmolyte, had no effect on ET-1 mRNA (1.1 ± 0.04 fold change and 1.07 ± .08 fold change vs. control, respectively; n=3, p<0.05) suggesting that a direct effect of NaCl, not osmolality, is responsible for the increase in ET-1 mRNA. Moreover, +40 mosm of sodium acetate (NaAc) or choline chloride (ChCl) resulted in an increase in ET-1 mRNA very similar to that seen by increasing NaCl (1.74±0.14 (NaCl), 1.54±0.05 (NaAc), and 1.59±0.03 (ChCl) fold change vs. control, n=3, p<0.05), suggesting that either the Na or Cl ion increases ET-1 expression. These data demonstrate that vascular endothelial cells express ET-1 in response to increases in NaCl concentration, and may be important in mediating the extrarenal inflammatory response to a high salt diet.

Functional analysis of the aquaporin gene family in Caenorhabditis elegans

2007 ◽  
Vol 292 (5) ◽  
pp. C1867-C1873 ◽  
Author(s):  
Chunyi George Huang ◽  
Todd Lamitina ◽  
Peter Agre ◽  
Kevin Strange
Keyword(s):  
Caenorhabditis Elegans ◽  
Gene Family ◽  
Fluorescent Protein ◽  
Water Channel ◽  
Cell Types ◽  
Culture Conditions ◽  
C Elegans ◽  
Hypotonic Stress ◽  
Aquaporin Gene ◽  
Green Fluorescent

Aquaporin channels facilitate the transport of water, glycerol, and other small solutes across cell membranes. The physiological roles of many aquaporins remain unclear. To better understand aquaporin function, we characterized the aquaporin gene family in the nematode Caenorhabditis elegans. Eight canonical aquaporin-encoding genes ( aqp) are present in the worm genome. Expression of aqp-2, aqp-3, aqp-4, aqp-6, or aqp-7 in Xenopus oocytes increased water permeability five- to sevenfold. Glycerol permeability was increased three to sevenfold by expression of aqp-1, aqp-3, or aqp-7. Green fluorescent protein transcriptional and translational reporters demonstrated that aqp genes are expressed in numerous C. elegans cell types, including the intestine, excretory cell, and hypodermis, which play important roles in whole animal osmoregulation. To define the role of C. elegans aquaporins in osmotic homeostasis, we isolated deletion alleles for four aqp genes, aqp-2, aqp-3, aqp-4, and aqp-8, which are expressed in osmoregulatory tissues and mediate water transport. Single, double, triple, and quadruple aqp mutant animals exhibited normal survival, development, growth, fertility, and movement under normal and hypertonic culture conditions. aqp-2; aqp-3; aqp-4; aqp-8 quadruple mutants exhibited a slight defect in recovery from hypotonic stress but survived hypotonic stress as well as wild-type animals. These results suggest that C. elegans aquaporins are not essential for whole animal osmoregulation and/or that deletion of aquaporin genes activates mechanisms that compensate for loss of water channel function.

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