Involvement and source of calcium in volume regulatory decrease of collapsed proximal convoluted tubule

1992 ◽  
Vol 263 (4) ◽  
pp. F656-F664 ◽  
Author(s):  
S. Breton ◽  
J. S. Beck ◽  
J. Cardinal ◽  
G. Giebisch ◽  
R. Laprade
Keyword(s):  
Proximal Tubules ◽  
Cell Swelling ◽  
Isotonic Solution ◽  
Tetraacetic Acid ◽  
Volume Regulatory Decrease ◽  
Hypotonic Shock ◽  
Initial Cell ◽  
A Value ◽  
20 Nm

We examined the role of Ca2+ in the volume regulatory decrease (VRD) of rabbit collapsed proximal tubules. Reduction of bath osmolality by 125 mosmol/kgH2O led to an initial cell swelling of 62.3 +/- 7.5% followed by a partial regulatory phase bringing cell volume to a value of 13.3 +/- 2.9% above control (n = 5). This swelling was accompanied by a transient intracellular Ca2+ ([Ca2+]i) increase from 174 +/- 33 to 306 +/- 67 nM (P < 0.05, n = 8). In the same condition, but in absence of extracellular Ca2+ ([Ca2+]e) [1 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA)], VRD following hypotonic shock was identical to that observed in presence of [Ca2+]e (n = 5), and [Ca2+]i increased transiently from 136 +/- 29 to 161 +/- 31 nM (P < 0.05, n = 5). Addition of 100 microM 8-(N,N-dimethylamino)octyl 3,4,5-trimethoxybenzoate hydrochloride (TMB-8), an agent known to inhibit Ca2+ release from intracellular stores, did not affect the initial cell swelling (63.4 +/- 4.2%), and VRD occurred to the same extent (25.0 +/- 7.1%, n = 4), although at a lower rate. In these conditions, [Ca2+]i, which was 113 +/- 30 nM in the isotonic solution, decreased progressively to 81 +/- 20 nM over the 5-min hypotonic period (n = 5). Mere preincubation with 100 microM TMB-8 before hypotonic shock led to a VRD identical to that observed in presence of Ca2+ and absence of TMB-8 while still blocking the Ca2+ release, with cell Ca2+ decreasing progressively from 179 +/- 32 to 87 +/- 21 nM (n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)

cAMP-stimulated rise of [Ca2+]i in rabbit connecting tubules: role of peritubular Ca

1990 ◽  
Vol 258 (3) ◽  
pp. F751-F755 ◽  
Author(s):  
J. E. Bourdeau ◽  
B. K. Eby
Keyword(s):  
Parathyroid Hormone ◽  
Ethylene Glycol ◽  
Cell Activation ◽  
Proximal Tubules ◽  
Tetraacetic Acid ◽  
Luminal Membrane ◽  
Dose Dependent Fashion ◽  
Dose Dependent

Parathyroid hormone (PTH) increases cytosolic free Ca concentration ([ Ca2+]i) by mechanisms that depend on extracellular Ca in both cultured renal proximal tubules and isolated rabbit connecting tubules (CNTs). In CNTs 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) mimics this action, implicating cAMP as a second messenger, and part of the rise, due to increased luminal membrane Ca entry, is likely related to Ca absorption. In cultured proximal tubules the rise in [Ca2+]i, presumably mediated by increased Ca entry across the basolateral plasmalemma, activates gluconeogenesis and shortens microvilli. In the present study we examined cAMP-mediated Ca entry across the basolateral membranes of CNT cells, an effect potentially related to cell activation. Single CNTs were dissected from rabbit kidneys and loaded with fura-2. [Ca2+]i was measured by dual-wavelength excitation during perfusion of isolated segments in vitro. With 1.8 or 2.0 mM Ca in the lumen and the bath, suffusate 8-BrcAMP increased [Ca2+]i within minutes in a dose-dependent fashion. The increase persisted as long as 8-BrcAMP was present and reversed on its withdrawal. With 0.1 microM Ca in the lumen and the bath, 8-BrcAMP, but not ionomycin, failed to increase [Ca2+]i, implying that extracellular Ca is the major source. In tubules perfused with 2 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid to eliminate luminal Ca, but suffused with 1.8 or 2.0 mM Ca, 8-BrcAMP increased [Ca2+]i (though less so than with Ca in the lumen), implying Ca entry across basolateral cell membranes. This rise in [Ca2+]i was attenuated markedly by the presence of 50 microM LaCl3 in the bath.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Calcein labelling and electrophysiology: insights on coral tissue permeability and calcification

2011 ◽  
Vol 279 (1726) ◽  
pp. 19-27 ◽  
Author(s):  
Eric Tambutté ◽  
Sylvie Tambutté ◽  
Natacha Segonds ◽  
Didier Zoccola ◽  
Alexander Venn ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Electrical Resistance ◽  
Sea Water ◽  
Intercellular Junctions ◽  
Coral Tissue ◽  
Ionic Permeability ◽  
A Value ◽  
Calcification Process ◽  
20 Nm

The mechanisms behind the transfer of molecules from the surrounding sea water to the site of coral calcification are not well understood, but are critical for understanding how coral reefs are formed. We conducted experiments with the fluorescent dye calcein, which binds to calcium and is incorporated into growing calcium carbonate crystals, to determine the permeability properties of coral cells and tissues to this molecule, and to determine how it is incorporated into the coral skeleton. We also compared rates of calcein incorporation with rates of calcification measured by the alkalinity anomaly technique. Finally, by an electrophysiological approach, we investigated the electrical resistance of coral tissues in order to better understand the role of tissues in ionic permeability. Our results show that (i) calcein passes through coral tissues by a paracellular pathway, (ii) intercellular junctions control and restrict the diffusion of molecules, (iii) intercellular junctions should have pores of a size higher than 13 Å and lower than 20 nm, and (iv) the resistance of the tissues owing to paracellular junctions has a value of 477 ± 21 Ohm cm 2 . We discuss the implication of our results for the transport of calcium involved in the calcification process.

Role of cytoskeleton in volume regulation of rabbit proximal tubule in dilute medium

1992 ◽  
Vol 262 (1) ◽  
pp. F144-F150 ◽  
Author(s):  
M. A. Linshaw ◽  
C. A. Fogel ◽  
G. P. Downey ◽  
E. W. Koo ◽  
A. I. Gotlieb
Keyword(s):  
Proximal Tubule ◽  
Volume Regulation ◽  
Cytochalasin B ◽  
Proximal Tubules ◽  
Hypotonic Medium ◽  
Microtubule Inhibitor ◽  
Volume Regulatory Decrease ◽  
Convoluted Tubules ◽  
Dilute Medium

When proximal tubules are immersed in hypotonic medium, they quickly swell to a peak volume. In a second, slower phase, termed volume regulatory decrease (VRD), they shrink as K, anion, and water leave the cells. We investigated the role of the cytoskeleton during this biphasic hypotonic volume regulatory response. Isolated, collapsed rabbit proximal convoluted tubules (PCT) were crimped tightly between two pipettes, and their volume was assessed optically. PCT volume increased to a peak 70-80% above baseline on sudden immersion in dilute medium (150 mosmol/kgH2O). After completing VRD, control tubules had regulated their volume 73 +/- 2% back toward baseline. Tubules exposed to the microtubule inhibitor vincristine (5 microM) regulated 75 +/- 2%. Tubules exposed to the microfilament inhibitor cytochalasin B (50 microM) regulated less (57 +/- 5%), and tubules exposed to both inhibitors regulated only 39 +/- 3% (P less than 0.01 vs. control). Hypotonic VRD was unimpaired in PCT loaded with NaCl by prior exposure to ouabain but was significantly reduced by cytochalasin B. We conclude that VRD is not cation specific and that intact microtubules and microfilaments play a synergistic role in the VRD of rabbit PCT in hyposmotic medium.

Endangered Butterflies and their Non-Native Host Plants: Examining Shifting Values of Belonging in Restoration

2019 ◽  
Vol 3 (1) ◽  
pp. 1-9
Author(s):  
Robert M. Anderson ◽  
Amy M. Lambert
Keyword(s):  
Ecological Restoration ◽  
Native Species ◽  
Puget Sound ◽  
A Value ◽  
The Social ◽  
Remote Island ◽  
Scientific Truth ◽  
Native Host

The island marble butterfly (Euchloe ausonides insulanus), thought to be extinct throughout the 20th century until re-discovered on a single remote island in Puget Sound in 1998, has become the focus of a concerted protection effort to prevent its extinction. However, efforts to “restore” island marble habitat conflict with efforts to “restore” the prairie ecosystem where it lives, because of the butterfly’s use of a non-native “weedy” host plant. Through a case study of the island marble project, we examine the practice of ecological restoration as the enactment of particular norms that define which species are understood to belong in the place being restored. We contextualize this case study within ongoing debates over the value of “native” species, indicative of deep-seated uncertainties and anxieties about the role of human intervention to alter or manage landscapes and ecosystems, in the time commonly described as the “Anthropocene.” We interpret the question of “what plants and animals belong in a particular place?” as not a question of scientific truth, but a value-laden construct of environmental management in practice, and we argue for deeper reflexivity on the part of environmental scientists and managers about the social values that inform ecological restoration.

Perempuan dan Liminalitas dalam Tradisi Perkawinan Adat di Timor Tengah Selatan

2020 ◽  
Vol 6 (1) ◽  
pp. 114
Author(s):  
Marsel Eliaser Liunokas
Keyword(s):  
Qualitative Research ◽  
Research Method ◽  
Literature Study ◽  
Qualitative Research Method ◽  
South Central ◽  
A Value ◽  
Traditional Marriage ◽  
The Village ◽  
As If

Timorese culture is patriarchal in that men are more dominant than women. As if women were not considered in traditional rituals so that an understanding was built that valued women lower than men. However, in contrast to the article to be studied, this would like to see the priority of women’s roles in traditional marriages in Belle village, South Central Timor. The role of women wiil be seen from giving awards to their parents called puah mnasi manu mnasi. This paper aims to look at the meaning of the rituals of puah mnasi maun mnasi and the role and strengths that women have in traditional marriage rituals in the village of Belle, South Central Timor. The method used for this research is a qualitative research method using interview techniques with a number of people in the Belle Villa community and literature study to strengthen this writing. Based on the data obtained this paper shows that the adat rituals of puah mnasi manu mnasi provide a value that can be learned, namely respect for women, togetherness between the two families, and brotherhood that is intertwined due to customary marital affrairs.

Influence of social networks on business processes’ development

2020 ◽  
Vol 19 (12) ◽  
pp. 2225-2252
Author(s):  
E.V. Popov ◽  
V.L. Simonova ◽  
O.V. Komarova ◽  
S.S. Kaigorodova
Keyword(s):  
Social Networks ◽  
Social Media ◽  
Business Models ◽  
Business Processes ◽  
Digital Economy ◽  
Theoretical Understanding ◽  
Sales Channels ◽  
A Value ◽  
The Impact

Subject. The emergence of new ways of interaction between sellers and buyers, the formation of new sales channels and product promotion based on the use of digital economy tools is at the heart of improving the business processes. Social networks became a tool for development; their rapid growth necessitates theoretical understanding and identification of potential application in enterprise's business process digitalization. Objectives. We explore the role of social media in the digitalization of business processes, systematize the impact of social networks on business processes of enterprises in the digital economy. Methods. The theoretical and methodological analysis of social networks as a tool for digitalization of company's business processes rests on the content analysis of domestic and foreign scientific studies, comparison, generalization and systematization. Results. We highlight the key effects of the impact of social networks on the business processes of the company; show that the digitalization of business processes should be considered in the context of a value-based approach, aimed at creating a value through the algorithmization of company operations. We determine that social networks are one of the most important tools for digitalization of company's business processes, as they have a high organizational and management potential. We also systematize the effects of social media on company's business processes. Conclusions. We present theoretical provisions of the impact of social networks on business processes of enterprises, which will enable to model and organize ideas about the development of digital ecosystems and the formation of business models.

scholarly journals Determining the Role of Acidity, Fate and Formation of IEPOX-Derived SOA in CMAQ

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 707
Author(s):  
Petros Vasilakos ◽  
Yongtao Hu ◽  
Armistead Russell ◽  
Athanasios Nenes
Keyword(s):  
Significant Influence ◽  
Organic Aerosol ◽  
Liquid Water Content ◽  
Anthropogenic Emissions ◽  
So2 Emissions ◽  
Aerosol Acidity ◽  
A Value ◽  
Future Emission ◽  
The Impact

Formation of aerosol from biogenic hydrocarbons relies heavily on anthropogenic emissions since they control the availability of species such as sulfate and nitrate, and through them, aerosol acidity (pH). To elucidate the role that acidity and emissions play in regulating Secondary Organic Aerosol (SOA), we utilize the 2013 Southern Oxidant and Aerosol Study (SOAS) dataset to enhance the extensive mechanism of isoprene epoxydiol (IEPOX)-mediated SOA formation implemented in the Community Multiscale Air Quality (CMAQ) model (Pye et al., 2013), which was then used to investigate the impact of potential future emission controls on IEPOX OA. We found that the Henry’s law coefficient for IEPOX was the most impactful parameter that controls aqueous isoprene OA products, and a value of 1.9 × 107 M atm−1 provides the best agreement with measurements. Non-volatile cations (NVCs) were found in higher-than-expected quantities in CMAQ and exerted a significant influence on IEPOX OA by reducing its production by as much as 30% when present. Consistent with previous literature, a strong correlation of isoprene OA with sulfate, and little correlation with acidity or liquid water content, was found. Future reductions in SO2 emissions are found to not affect this correlation and generally act to increase the sensitivity of IEPOX OA to sulfate, even in extreme cases.

A meta-analysis and review examining a possible role for oxidative stress and singlet oxygen in diverse diseases

2017 ◽  
Vol 474 (16) ◽  
pp. 2713-2731 ◽  
Author(s):  
Athinoula L. Petrou ◽  
Athina Terzidaki
Keyword(s):  
Oxidative Stress ◽  
Excited State ◽  
Singlet Oxygen ◽  
Ground State ◽  
Meta Analysis ◽  
Common Mechanism ◽  
High Electron ◽  
A Value ◽  
First Excited State

From kinetic data (k, T) we calculated the thermodynamic parameters for various processes (nucleation, elongation, fibrillization, etc.) of proteinaceous diseases that are related to the β-amyloid protein (Alzheimer's), to tau protein (Alzheimer's, Pick's), to α-synuclein (Parkinson's), prion, amylin (type II diabetes), and to α-crystallin (cataract). Our calculations led to ΔG≠ values that vary in the range 92.8–127 kJ mol−1 at 310 K. A value of ∼10–30 kJ mol−1 is the activation energy for the diffusion of reactants, depending on the reaction and the medium. The energy needed for the excitation of O2 from the ground to the first excited state (1Δg, singlet oxygen) is equal to 92 kJ mol−1. So, the ΔG≠ is equal to the energy needed for the excitation of ground state oxygen to the singlet oxygen (1Δg first excited) state. The similarity of the ΔG≠ values is an indication that a common mechanism in the above disorders may be taking place. We attribute this common mechanism to the (same) role of the oxidative stress and specifically of singlet oxygen, (1Δg), to the above-mentioned processes: excitation of ground state oxygen to the singlet oxygen, 1Δg, state (92 kJ mol−1), and reaction of the empty π* orbital with high electron density regions of biomolecules (∼10–30 kJ mol−1 for their diffusion). The ΔG≠ for cases of heat-induced cell killing (cancer) lie also in the above range at 310 K. The present paper is a review and meta-analysis of literature data referring to neurodegenerative and other disorders.

Measurements of cell adhesion

Development ◽  
1973 ◽  
Vol 30 (2) ◽  
pp. 499-509
Author(s):  
Janet E. Hornby
Keyword(s):  
Cell Types ◽  
Random Motion ◽  
Chick Embryos ◽  
Collision Efficiency ◽  
20 Nm ◽  
Kidney Liver ◽  
Different Cell Types ◽  
Laminar Shear ◽  
Lyophobic Sols

Cell suspensions were prepared from the kidney, liver and heart of chick embryos of 5 or 8 days of incubation, and from the limb-buds of chick embryos of 5, 6, 7, 8 or 9 days of incubation. When these suspensions were aggregated under laminar shear in a Couette viscometer or random motion in a reciprocating shaker they obeyed the theoretical relationships derived for flocculating lyophobic sols. The values of the collision efficiency found for the different cell types under given conditions were used to calculate the force of interaction between cells of each type. The force of interaction ranged between 9 × 10−11 N (8-day heart) and 3 × 10−9 N (8-day liver). The forces of interaction between cells appear to be responsible for aligning the membranes of adjacent cells with a 10–20 nm gap. It is possible to arrange the cell types in a hierarchy based on the forces of interaction between them. The possible role of these forces in cell specificity is considered.

The role of the media in the formation of shame in the national consciousness

2021 ◽  
Author(s):  
Alaigul Karabaevna Bekboeva
Keyword(s):  
National Identity ◽  
Social Meaning ◽  
National Consciousness ◽  
Social Phenomenon ◽  
Human Relationships ◽  
Social Existence ◽  
A Value ◽  
State And Society ◽  
The Media

This article considers the role of the media as a partner of the state and society, as well as spontaneity. Due to this, media serve as one of the factors in the formation of national self-consciousness and its elements, such as shame. The author analyzes such element of national identity as national shame. It is proved that national shame as a social phenomenon has a social meaning of the regulator of human relationships in social existence. It is noted that national shame is socially determined, has a permanent character, and its socially significant semantic principles are passed from generation to generation as a form of behavior through implantation and interspersing it as a daily norm of people's behavior, giving each act a value-significant meaning.

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