K+ conductance activated by osmotic cell swelling or by leukotriene D4 in ehrlich cells.

2000 ◽  
Vol 126 ◽  
pp. 135
Author(s):  
M.I. Niemeyer ◽  
C. Hougaard ◽  
E.K. Hoffmann ◽  
F. Jørgensen ◽  
A. Stutzin ◽  
...  
Keyword(s):  
Cell Swelling ◽  
Leukotriene D4 ◽  
Ehrlich Cells

Activation of Cl-dependent K transport in Ehrlich ascites tumor cells

1986 ◽  
Vol 251 (3) ◽  
pp. C369-C379 ◽  
Author(s):  
B. Kramhoft ◽  
I. H. Lambert ◽  
E. K. Hoffmann ◽  
F. Jorgensen
Keyword(s):  
Regulatory Volume Decrease ◽  
Extracellular Ph ◽  
Cell Swelling ◽  
Disulfonic Acid ◽  
Cell Shrinkage ◽  
Ehrlich Cells ◽  
Ehrlich Ascites ◽  
Dependent Component ◽  
Ca Depletion ◽  
Volume Decrease

N-ethylmaleimide (NEM) treatment of steady-state Ehrlich cells induces a substantial net loss of cellular KCl and cell shrinkage. The majority of the initial K loss is Cl dependent. From estimates of membrane potential it is concluded that the NEM-induced KCl loss is electroneutral. The effect of NEM on H extrusion by cells in 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS)-containing medium showed that only an insignificant part of the K loss could be attributed to an activation of a K-H exchange system. Consequently, NEM appears to activate a K-Cl cotransport, which causes cell shrinkage. The anion preference of the K loss is Cl greater than Br much greater than SCN = NO3. NEM also seems to inhibit a Cl-dependent Na uptake previously described in shrunken cells. Addition of NEM to cells undergoing regulatory volume decrease after swelling in hyposmotic media results in a Cl-dependent acceleration of cell shrinkage, suggesting that a Cl-dependent component of K efflux is induced by NEM also in swollen cells. A Cl-dependent K efflux is also activated in Ca-depleted cells or at reduced extracellular pH after cell swelling. Under isotonic conditions activation of Cl-dependent K flux after Ca depletion or pH reduction could not be demonstrated. The combined results show that Ehrlich cells possess a latent K-Cl cotransport that becomes active after changes in the state of SH groups, regardless of the initial cell volume. A similar K-Cl cotransport is activated in hypotonically swollen cells after Ca depletion or after reduction of the extracellular pH.

Effect of somatostatin on cell volume, Cl- currents, and transepithelial Cl- transport in rat distal colon

1994 ◽  
Vol 266 (6) ◽  
pp. G1043-G1052 ◽  
Author(s):  
M. Diener ◽  
V. Gartmann
Keyword(s):  
Distal Colon ◽  
Receptor Blocker ◽  
Cell Swelling ◽  
Lipoxygenase Inhibitor ◽  
Leukotriene D4 ◽  
Cl Channel ◽  
Camp Pathway ◽  
Rat Distal Colon ◽  
D4 Receptor ◽  
Stimulation Of

Somatostatin (10(-10)-10(-7) mol/l) caused a concentration-dependent increase of the diameter of isolated crypts from the rat distal colon. Cell swelling was restricted to the upper one-third of the crypt and was dependent on the presence of Na+ and Cl- ions, indicating that it was caused by the stimulation of NaCl absorption by the hormone. Swelling was followed by a regulatory volume decrease, which could be inhibited by K+ and Cl- channel blockers. Also a lipoxygenase inhibitor and a leukotriene D4 receptor blocker inhibited volume regulation. Whole cell recordings performed in parallel revealed that somatostatin induced a depolarization of the cells at the upper one-third of the crypt but had no effect in the deeper parts of the crypt. This depolarization was concomitant with an increase in Cl- (and partially also HCO3-) conductance and was suppressed by a leukotriene D4 receptor blocker. In contrast, when Cl- secretion was stimulated by vasoactive intestinal peptide, a secretagogue acting on the adenosine 3',5'-cyclic monophosphate (cAMP) pathway, the effect of somatostatin was reversed from a depolarization into a hyperpolarization, an effect that was also observed in deeper parts of the crypt. Consequently, in crypts stimulated via the cAMP pathway, somatostatin inhibits the activation of apical Cl- channels. Somatostatin also partially inhibited the increase of K+ conductance induced by carbachol, a secretagogue acting on the Ca2+ pathway. Ussing chamber experiments showed that somatostatin caused a concentration-dependent decrease of short-circuit current. This decrease was dependent on the presence of Cl- and HCO3- ions. Measurements of unidirectional ion fluxes indicated that somatostatin stimulated Cl- absorption by an increase of the mucosa-to-serosa flux of this ion. The stimulation of Cl- absorption was completely suppressed by a Cl- channel blocker and by a lipoxygenase inhibitor. Consequently, the activation of a volume/leukotriene-sensitive basolateral Cl- conductance seems to be involved in the stimulation of Cl- absorption by somatostatin.

Na+-K+-2Cl−cotransport in Ehrlich cells: regulation by protein phosphatases and kinases

1998 ◽  
Vol 275 (1) ◽  
pp. C239-C250 ◽  
Author(s):  
Thomas Krarup ◽  
Lene D. Jakobsen ◽  
Bo S. Jensen ◽  
Else K. Hoffmann
Keyword(s):  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Cell Swelling ◽  
Cell Shrinkage ◽  
Volume Increase ◽  
Ehrlich Cells ◽  
Dependent Inhibition ◽  
Cotransport System

To identify protein kinases (PK) and phosphatases (PP) involved in regulation of the Na+-K+-2Cl−cotransporter in Ehrlich cells, the effect of various PK and PP inhibitors was examined. The PP-1, PP-2A, and PP-3 inhibitor calyculin A (Cal-A) was a potent activator of Na+-K+-2Cl−cotransport (EC50 = 35 nM). Activation by Cal-A was rapid (<1 min) but transient. Inactivation is probably due to a 10% cell swelling and/or the concurrent increase in intracellular Cl− concentration. Cell shrinkage also activates the Na+-K+-2Cl−cotransport system. Combining cell shrinkage with Cal-A treatment prolonged the cotransport activation compared with stimulation with Cal-A alone, suggesting PK stimulation by cell shrinkage. Shrinkage-induced cotransport activation was pH and Ca2+/calmodulin dependent. Inhibition of myosin light chain kinase by ML-7 and ML-9 or of PKA by H-89 and KT-5720 inhibited cotransport activity induced by Cal-A and by cell shrinkage, with IC50 values similar to reported inhibition constants of the respective kinases in vitro. Cell shrinkage increased the ML-7-sensitive cotransport activity, whereas the H-89-sensitive activity was unchanged, suggesting that myosin light chain kinase is a modulator of the Na+-K+-2Cl−cotransport activity during regulatory volume increase.

Imaging NMDA- and kainate-induced intrinsic optical signals from the hippocampal slice

1996 ◽  
Vol 76 (4) ◽  
pp. 2707-2717 ◽  
Author(s):  
R. D. Andrew ◽  
J. R. Adams ◽  
T. M. Polischuk
Keyword(s):  
Nmda Receptor ◽  
Receptor Antagonist ◽  
Ampa Receptors ◽  
Hippocampal Slice ◽  
Field Potential ◽  
Nmda Receptor Antagonist ◽  
Light Transmittance ◽  
Stratum Radiatum ◽  
Cell Swelling ◽  
Tissue Resistance

1. Brain ischemia causes excess release and accumulation of glutamate that binds to postsynaptic receptors. This opens ionotropic channels that mediate neuronal depolarization and ionic fluxes that can lead to neuronal death. 2. The CA1 pyramidal cell region of the hippocampus is particularly susceptible to this neurotoxic process. Brain cell swelling is considered an early excitotoxic event, but remains poorly under stood and documented. As cells swell, light transmittance (LT) increases through brain tissue, so we hypothesized that brief exposure to glutamate agonists would elicit cell swelling that could be imaged in real time in the hippocampal slice. 3. A 1-min bath application of 100 microM N-methyl-D-aspartate (NMDA) or 100 microM kainate at 22 degrees C greatly increased LT, particularly in the dendritic regions of CA1. The response peaked by 2-3 min and slowly reversed over the subsequent 20 min following exposure. Peak LT increases were > 50% in CA1 stratum radiatum and > 20% in both CA1 stratum oriens and the dendritic region of the dentate gyrus, all areas with a high concentration of NMDA and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors. The CA3 stratum radiatum, which contains fewer of these receptors, showed a comparatively small LT increase. 4. The NMDA receptor antagonist 2-amino-5-phosphonovalerate (AP-5) [but not 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)] blocked the CA1 response to NMDA, whereas the non-NMDA receptor antagonist CNQX (but not AP-5) blocked the response to kainate. The relative tissue resistance measured across CA1 stratum radiatum increased after NMDA or kainate exposure with a time course similar to the LT change described above. The increase in relative tissue resistance was blocked by kynurenate, a nonspecific glutamate antagonist. Increases in both LT and tissue resistance provide two independent lines of evidence that cell swelling rapidly developed in CA1 dendritic areas after activation of NMDA or AMPA receptors. 5. This swelling at 22 degrees C was accompanied by a temporary loss of the evoked CA1 field potential. However, at 37 degrees C the dendritic swelling rapidly progressed to an irreversible LT increase (swelling) of the CA1 cell bodies accompanied by a permanent loss of the evoked field. 6. We propose that dendritic swelling mediated by NMDA and AMPA receptors is an early excitotoxic event that can herald permanent damage to CA1 neurons, those cells most vulnerable to ischemic insult.

ATP potently modulates anion channel-mediated excitatory amino acid release from cultured astrocytes

2002 ◽  
Vol 283 (2) ◽  
pp. C569-C578 ◽  
Author(s):  
Alexander A. Mongin ◽  
Harold K. Kimelberg
Keyword(s):  
Amino Acid ◽  
Excitatory Amino Acid ◽  
Atp Release ◽  
Anion Channel ◽  
P2y Receptors ◽  
Cell Swelling ◽  
Channel Blockers ◽  
Medium Osmolarity ◽  
Subsequent Activation

Volume-dependent ATP release and subsequent activation of purinergic P2Y receptors have been implicated as an autocrine mechanism triggering activation of volume-regulated anion channels (VRACs) in hepatoma cells. In the brain ATP is released by both neurons and astrocytes and participates in intercellular communication. We explored whether ATP triggers or modulates the release of excitatory amino acid (EAAs) via VRACs in astrocytes in primary culture. Under basal conditions exogenous ATP (10 μM) activated a small EAA release in 70–80% of the cultures tested. In both moderately (5% reduction of medium osmolarity) and substantially (35% reduction of medium osmolarity) swollen astrocytes, exogenous ATP greatly potentiated EAA release. The effects of ATP were mimicked by P2Y agonists and eliminated by P2Y antagonists or the ATP scavenger apyrase. In contrast, the same pharmacological maneuvers did not inhibit volume-dependent EAA release in the absence of exogenous ATP, ruling out a requirement of autocrine ATP release for VRAC activation. The ATP effect in nonswollen and moderately swollen cells was eliminated by a 5–10% increase in medium osmolarity or by anion channel blockers but was insensitive to tetanus toxin pretreatment, further supporting VRAC involvement. Our data suggest that in astrocytes ATP does not trigger EAA release itself but acts synergistically with cell swelling. Moderate cell swelling and ATP may serve as two cooperative signals in bidirectional neuron-astrocyte communication in vivo.

Unique coronary vasodilator induction by leukotriene D4

1985 ◽  
Vol 249 (3) ◽  
pp. H698-H702 ◽  
Author(s):  
D. Ezra ◽  
G. Feuerstein ◽  
J. F. Czaja ◽  
F. R. Laurindo ◽  
C. K. Finton ◽  
...  
Keyword(s):  
Coronary Flow ◽  
Platelet Rich Plasma ◽  
Platelet Activating Factor ◽  
Adenosine Diphosphate ◽  
Coronary Vein ◽  
Marked Rise ◽  
Leukotriene D4 ◽  
Coronary Vasodilator ◽  
Myocardial Area

Coronary blood flow (CBF) and myocardial contractility decrease markedly in response to intracoronary administration of leukotriene D4 (LTD4). With steady infusion, however, both CBF and contractility escape, approaching preinfusion values despite ongoing LTD4 administration. To clarify the mechanism of this escape, we reinfused plasma from the coronary vein draining the myocardial area receiving LTD4. Introducing this plasma into a coronary artery caused a marked rise in coronary flow for the duration of the plasma infusion. Coronary flow reduction with vasopressin or mechanical occlusion matching that caused by LTD4 failed to elicit vasodilator production. Thus a unique coronary vasodilator factor is induced by LTD4. Whole blood or platelet-rich plasma incubated with LTD4 in vitro produced the same pattern of coronary dilation on intracoronary infusion; LTD4 incubation with platelet-poor plasma failed to elicit a vasodilation. The vasodilator factor is stable and is not potassium, a prostaglandin, catecholamine, histamine, serotonin, adenosine, adenosine diphosphate, or platelet-activating factor. Production of this leukotriene-induced vasodilator factor may account for the escape from LTD4-induced coronary constriction.

scholarly journals A Novel Method Facilitating the Simple and Low-Cost Preparation of Human Osteochondral Slice Explants for Large-Scale Native Tissue Analysis

2021 ◽  
Vol 22 (12) ◽  
pp. 6394
Author(s):  
Jacob Spinnen ◽  
Lennard K. Shopperly ◽  
Carsten Rendenbach ◽  
Anja A. Kühl ◽  
Ufuk Sentürk ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Viability ◽  
Large Scale ◽  
Marker Gene ◽  
Cell Swelling ◽  
Tissue Cell ◽  
Joint Research ◽  
Sample Number ◽  
Tnf Α ◽  
Novel Method

For in vitro modeling of human joints, osteochondral explants represent an acceptable compromise between conventional cell culture and animal models. However, the scarcity of native human joint tissue poses a challenge for experiments requiring high numbers of samples and makes the method rather unsuitable for toxicity analyses and dosing studies. To scale their application, we developed a novel method that allows the preparation of up to 100 explant cultures from a single human sample with a simple setup. Explants were cultured for 21 days, stimulated with TNF-α or TGF-β3, and analyzed for cell viability, gene expression and histological changes. Tissue cell viability remained stable at >90% for three weeks. Proteoglycan levels and gene expression of COL2A1, ACAN and COMP were maintained for 14 days before decreasing. TNF-α and TGF-β3 caused dose-dependent changes in cartilage marker gene expression as early as 7 days. Histologically, cultures under TNF-α stimulation showed a 32% reduction in proteoglycans, detachment of collagen fibers and cell swelling after 7 days. In conclusion, thin osteochondral slice cultures behaved analogously to conventional punch explants despite cell stress exerted during fabrication. In pharmacological testing, both the shorter diffusion distance and the lack of need for serum in the culture suggest a positive effect on sensitivity. The ease of fabrication and the scalability of the sample number make this manufacturing method a promising platform for large-scale preclinical testing in joint research.

scholarly journals Immunohistopathological response against anisakid nematode larvae and a coccidian in Micromesistius poutassou from NE Atlantic waters

2021 ◽  
Vol 95 ◽  
Author(s):  
B. Sayyaf Dezfuli ◽  
E. Simoni ◽  
G. Bosi ◽  
M. Palomba ◽  
S. Mattiucci ◽  
...  
Keyword(s):  
Sensu Stricto ◽  
Cell Swelling ◽  
Epithelioid Cells ◽  
Larval Stages ◽  
The North ◽  
Eastern Atlantic Ocean ◽  
Larval Infection ◽  
High Infection ◽  
North Eastern ◽  
Multilocus Approach

Abstract A survey on Anisakis simplex (sensu stricto (s.s.)) from blue whiting, Micromesistius poutassou, in the north-eastern Atlantic Ocean revealed the occurrence of high infection levels of third larval stages in visceral organs and flesh. Larvae were genetically identified with a multilocus approach as A. simplex (s.s.). Histochemical, immunohistochemical and ultrastructural observations were conducted on 30 M. poutassou specimens. Gonads, pyloric caeca and flesh harboured encapsulated larvae of A. simplex (s.s.) but no intense host reaction was encountered around the parasite in the above organs. In the liver, the most infected organ, the larvae co-occurred with the coccidian Goussia sp. Within the granuloma around the A. simplex (s.s.) larvae, two concentric layers were recognized, an inner mostly comprising electron-dense epithelioid cells and an outer layer made of less electron-dense epithelioid cells. Macrophages and macrophage aggregates (MAs) were abundant out of the granulomas, scattered in parenchyma, and inside the MAs, the presence of engulfed Goussia sp. was frequent. In liver tissue co-infected with Goussia sp. and A. simplex (s.s.), hepatocytes showed cytoplasmic rarefaction and acute cell swelling. Results suggest that the host-induced encapsulation of A. simplex (s.s.) larvae is a strategic compromise to minimize collateral tissue damage around the larval infection sites, to facilitate the survival of both parasite and host.

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