scholarly journals Hypertonic stress increases the Na+ conductance of rat hepatocytes in primary culture.

1995 ◽  
Vol 105 (4) ◽  
pp. 507-535 ◽  
Author(s):  
F Wehner ◽  
H Sauer ◽  
R K Kinne
Keyword(s):  
Cell Membrane ◽  
Primary Culture ◽  
Regulatory Volume Decrease ◽  
Rat Hepatocytes ◽  
Laser Scanning Microscopy ◽  
Specific Cell ◽  
Volume Increase ◽  
Regulatory Volume Increase ◽  
Hypertonic Stress ◽  
Cell Volumes

We studied the ionic mechanisms underlying the regulatory volume increase of rat hepatocytes in primary culture by use of confocal laser scanning microscopy, conventional and ion-sensitive microelectrodes, cable analysis, microfluorometry, and measurements of 86Rb+ uptake. Increasing osmolarity from 300 to 400 mosm/liter by addition of sucrose decreased cell volumes to 88.6% within 1 min; thereafter, cell volumes increased to 94.1% of control within 10 min, equivalent to a regulatory volume increase (RVI) by 44.5%. This RVI was paralleled by a decrease in cell input resistance and in specific cell membrane resistance to 88 and 60%, respectively. Ion substitution experiments (high K+, low Na+, low Cl-) revealed that these membrane effects are due to an increase in hepatocyte Na+ conductance. During RVI, ouabain-sensitive 86Rb+ uptake was augmented to 141% of control, and cell Na+ and cell K+ increased to 148 and 180%, respectively. The RVI, the increases in Na+ conductance and cell Na+, as well as the activation of Na+/K(+)-ATPase were completely blocked by 10(-5) mol/liter amiloride. At this concentration, amiloride had no effect on osmotically induced cell alkalinization via Na+/H+ exchange. When osmolarity was increased from 220 to 300 mosm/liter (by readdition of sucrose after a preperiod of 15 min in which the cells underwent a regulatory volume decrease, RVD) cell volumes initially decreased to 81.5%; thereafter cell volumes increased to 90.8% of control. This post-RVD-RVI of 55.0% is also mediated by an increase in Na+ conductance. We conclude that rat hepatocytes in confluent primary culture are capable of RVI as well as of post-RVD-RVI. In this system, hypertonic stress leads to a considerable increase in cell membrane Na+ conductance. In concert with conductive Na+ influx, cell K+ is then increased via activation of Na+/K(+)-ATPase. An additional role of Na+/H+ exchange in the volume regulation of rat hepatocytes remains to be defined.

Responses of lymphocytes to anisotonic media: volume-regulating behavior

1984 ◽  
Vol 246 (3) ◽  
pp. C204-C215 ◽  
Author(s):  
S. Grinstein ◽  
A. Rothstein ◽  
B. Sarkadi ◽  
E. W. Gelfand
Keyword(s):  
Regulatory Volume Decrease ◽  
Lymphocyte Subpopulations ◽  
Lymphoid Cells ◽  
Ionophore A23187 ◽  
Volume Increase ◽  
Regulatory Volume Increase ◽  
Cytoplasmic Acidification ◽  
Tissue Of Origin ◽  
Volume Decrease ◽  
Media Volume

The regulatory responses elicited in lymphoid cells suspended in anisotonic media are reviewed. The immediate response approximates osmometric behavior. In addition, in hypotonic media, the initial osmometric swelling is followed by a regulatory volume decrease (RVD), which is associated with KCl loss. The volume-induced effluxes of K+ and Cl- are mediated by two independent conductive pathways. Ca2+-depletion experiments and studies of inhibitor susceptibility suggest that Ca2+ may mediate the activation of the K+ pathway. The responses of the two main lymphocyte subpopulations to hypotonic challenge are different. RVD is much more rapid in T- than in B-cells, regardless of their tissue of origin. Under certain conditions, shrunken lymphocytes will regain their initial volume. This regulatory volume increase (RVI) is due to NaCl uptake, followed by a secondary exchange of Na+ for K+ via the Na+-K+ pump. Na+ is primarily taken up in exchange for H+ through an amiloride-sensitive pathway, whereas Cl- enters in exchange for HCO-3 (or OH-). Anion and cation fluxes responsible for RVI are electroneutral. Some of the volume-sensitive pathways can also be activated in isotonic cells. The conductive K+ pathway is activated by Ca2+ plus ionophore A23187, and the Na+-H+ exchanger can be activated by cytoplasmic acidification. The responses of lymphocytes to anisotonic challenge are compared with those of other cells, and the possible significance of the volume-induced fluxes is discussed.

Effects of osmotic stresses on isolated rat hepatocytes. I. Ionic mechanisms of cell volume regulation

1990 ◽  
Vol 258 (2) ◽  
pp. G290-G298
Author(s):  
J. G. Corasanti ◽  
D. Gleeson ◽  
J. L. Boyer
Keyword(s):  
Cell Volume ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Rat Hepatocytes ◽  
Relative Volume ◽  
Disulfonic Acid ◽  
Isolated Rat Hepatocytes ◽  
Hypertonic Stress ◽  
Anion Conductance ◽  
Ionic Mechanisms

Isolated hepatocyte suspensions were exposed to hypotonic and hypertonic stresses and serial cell volume measurements were made with an electronic particle size analyzer. With the exposure to hypotonic (160 mosM) buffer, hepatocytes swelled within 30-60 s as osomometers [relative volume (RV) = 1.44 +/- 0.08] and subsequently underwent regulatory volume decrease (RVD) back toward the resting (isotonic) level (1.16 +/- 0.05). This volume recovery was blocked by 65 mM extracellular K+ concentration and inhibited by barium (1 mM) and quinine (0.5 mM) but not by bumetanide (0.1 mM). Chloride depletion inhibited RVD by approximately 40% while 0.5 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) blocked the recovery by almost 90%. Calcium deprivation had no effect on RVD, nor did ouabain, amiloride, or sodium replacement. When exposed to buffer made hypertonic by addition of 200 mM sucrose, cells shrunk as osmometers (RV = 0.74 +/- 0.02) but did not exhibit regulatory volume increase (RVI). However, when cells that had first undergone RVD were reexposed to isotonic medium (relative hypertonic stress) RVI could be demonstrated from RV 0.77 +/- 0.17 to 0.91 +/- 0.20. This response was dependent on sodium, partially dependent on bicarbonate and chloride, and inhibited by the Na(+)-H+ exchange inhibitor amiloride (1 mM) but not by DIDS. Our findings suggest that RVD in rat hepatocytes is mediated by quinine- and barium-sensitive K+ conductance and DIDS-sensitive anion conductance, which is partly accounted for by Cl-; RVI is mediated by activation of Na(+)-H+ exchange coupled with a bicarbonate- and chloride-dependent but DIDS-insensitive process.

Stimulation of regulatory volume increase (RVI) in avian articular chondrocytes by gadolinium chloride

2010 ◽  
Vol 88 (3) ◽  
pp. 505-512 ◽  
Author(s):  
Sang-Bing Ong ◽  
Dinesh Shah ◽  
Ala Qusous ◽  
Simon M. Jarvis ◽  
Mark J.P. Kerrigan
Keyword(s):  
Actin Cytoskeleton ◽  
Articular Chondrocytes ◽  
Cell Volume Regulation ◽  
Extracellular Calcium ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Gadolinium Chloride ◽  
Volume Increase ◽  
Regulatory Volume Increase ◽  
Volume Recovery

Chondrocytes, the resident cell-type of articular cartilage, are responsible for the regulation of the extracellular matrix (ECM) in response to their physico-chemical environment. Due to the nature of cartilage loading, chondrocytes are exposed to constant changes in extracellular osmolality with a gradual increase throughout the day. As an increase in osmolality attenuates matrix synthesis, we have studied cell volume regulation (regulatory volume increase (RVI)) after hypertonic challenge and the regulation of RVI by the actin cytoskeleton. Using freshly isolated avian articular chondrocytes, changes in actin organisation were studied by confocal laser scanning microscopy following a 43% increase in extracellular osmolality. Using calcein-loading chondrocytes, the capacity for RVI was determined and the rate of volume recovery (t1/2) mathematically extrapolated. Following an increase in extracellular osmolality there was a significant increase (p < 0.05) in cortical actin, inhibited by the removal of extracellular calcium EGTA or by the addition of 100 µmol·L–1 gadolinium chloride. Most cells exhibited slow RVI (t1/2 = 55.5 ± 5.5 min), whereby inhibition of actin polymerisation by gadolinium chloride or the removal of extracellular calcium significantly increased the rate of volume recovery via a bumetanide-sensitive pathway (t1/2 of 29.6 ± 6.5 min and 13.8 ± 3.1 min, respectively). These data suggest the Na+–K+–2Cl– (NKCC) co-transporter regulated by the actin cytoskeleton is involved in avian chondrocyte RVI.

Na+/H+ exchange and osmotic shrinkage in isolated trout hepatocytes

1997 ◽  
Vol 200 (17) ◽  
pp. 2369-2376 ◽  
Author(s):  
B Fossat ◽  
J Porthé-Nibelle ◽  
S Pedersen ◽  
B Lahlou
Keyword(s):  
Rainbow Trout ◽  
Intracellular Ph ◽  
Extracellular Ph ◽  
Hypertonic Medium ◽  
Volume Increase ◽  
Regulatory Volume Increase ◽  
Hypertonic Stress ◽  
Amiloride Derivatives ◽  
Na Uptake ◽  
Rainbow Trout Liver

The ability of rainbow trout liver cells to regulate their intracellular pH (pHi) was studied using two methods on hepatocytes isolated by collagenase digestion: (i) by monitoring pHi with the fluorescent dye BCECF-AM, and (ii) by measuring the amiloride-sensitive uptake of 22Na, which represents Na+/H+ exchange. In low-Na+ medium (&frac34;16mmoll-1), Na+ uptake was reduced by approximately 70% in the presence of amiloride derivatives (DMA or MPA, 10(-4)moll-1). Changing separately either the extracellular pH (pHe) or the intracellular pH (pHi, clamped by treating the cells with nigericin in the presence of 140mmoll-1 K+) between 6 and 8 induced an increase in the rate of Na+ uptake when pHe was raised or when pHi was reduced. When transferred to hypertonic medium, hepatocytes shrank to nearly 72% of their initial volume, and thereafter a slow and partial regulatory volume increase phase was observed, with an increase in the amiloride-sensitive rate of Na+ uptake and an increase in intracellular pH. As DIDS-sensitive Cl- uptake was concomitantly enhanced, it is suggested that hypertonic stress activates Na+/H+ and Cl-/HCO3- exchange.

Ion transport asymmetry and functional coupling in bovine pigmented and nonpigmented ciliary epithelial cells

1994 ◽  
Vol 266 (5) ◽  
pp. C1210-C1221 ◽  
Author(s):  
J. L. Edelman ◽  
G. Sachs ◽  
J. S. Adorante
Keyword(s):  
Transport Properties ◽  
Aqueous Humor ◽  
Lucifer Yellow ◽  
Regulatory Volume Decrease ◽  
Ciliary Epithelium ◽  
Functional Coupling ◽  
Volume Increase ◽  
Regulatory Volume Increase ◽  
Cell Sizing ◽  
Volume Decrease

The solute and water transport properties of the bovine ciliary epithelium were studied using isolated pigmented (PE) and nonpigmented (NPE) cells. It was shown that these cells were functionally coupled by demonstrating dye diffusion between paired PE and NPE cells after microinjection of lucifer yellow. Electronic cell sizing was used to measure cell volume changes of isolated PE and NPE cells in suspension after anisosmotic perturbations and after transport inhibition under isosmotic conditions. The PE cells showed the presence of a regulatory volume increase when subjected to osmotic shrinkage with NaCl, whereas the NPE cells did not demonstrate a regulatory volume increase under these conditions. In contrast, the NPE cells exhibited a regulatory volume decrease when subjected to osmotic swelling, whereas the PE cells did not recover from swelling. The regulatory volume decrease in NPE cells was inhibited by increased bath K or pretreatment with quinine (1 mM). The presence of a bumetanide-sensitive mechanism capable of moving measurable amounts of solute and water, probably Na-K-2Cl cotransport, was demonstrated in the PE cells but absent in the NPE cells. Bumetanide produced a dose-dependent shrinkage of PE cells at concentrations as low as 1 microM. Isosmotically reducing bath Cl, Na, or K concentration caused a rapid shrinkage of PE cells that was bumetanide inhibitable. The asymmetry of transport properties in PE and NPE cells supports a functional syncytium model of aqueous humor formation (39) across the two layers of the ciliary epithelium wherein ion uptake from the blood is carried out by the PE cells and ion extrusion by the NPE cells. Gap-junction coupling between the cells allows the ions taken up by the PE cells to move into the NPE cells. Extrusion of Na by the Na-K pump across the aqueous facing (basolateral) membranes of the NPE cells, most likely accompanied by Cl, determines the formation of the aqueous humor.

scholarly journals Regulatory Volume Increase and Regulatory Volume Decrease Responses in HL-1 Atrial Myocytes

2014 ◽  
Vol 33 (6) ◽  
pp. 1745-1757 ◽  
Author(s):  
Veronica I. Cacace ◽  
Andres G. Finkelsteyn ◽  
Laura M. Tasso ◽  
Carlos F. Kusnier ◽  
Karina A. Gomez ◽  
...  
Keyword(s):  
Regulatory Volume Decrease ◽  
Atrial Myocytes ◽  
Volume Increase ◽  
Regulatory Volume Increase ◽  
Volume Decrease

scholarly journals Vasopressin Neurons Respond to Hyperosmotic Stimulation with Regulatory Volume Increase and Secretory Volume Decrease by Activating Ion Transporters and Ca2+ Channels

2021 ◽  
Vol 55 (S1) ◽  
pp. 119-134
Keyword(s):  
Regulatory Volume Decrease ◽  
The Body ◽  
Cell Swelling ◽  
Ion Transporters ◽  
Cell Shrinkage ◽  
Volume Increase ◽  
Regulatory Volume Increase ◽  
Vasopressin Neurons ◽  
Ca2 Channels ◽  
Volume Decrease

BACKGROUND/AIMS: Arginine vasopressin (AVP) neurons play an important role for sensing a change in the plasma osmolarity and thereby responding with regulated AVP secretion in order to maintain the body fluid homeostasis. The osmo-sensing processes in magnocellular neurosecretory cells (MNCs) including AVP and oxytocin (OXT) neurons of the hypothalamus were reported to be coupled to sustained osmotic shrinkage or swelling without exhibiting discernible cell volume regulation. Since increasing evidence has shown some important differences in properties between AVP and OXT neurons, osmotic volume responses are to be reexamined with distinguishing these cell types from each other. We previously reported that AVP neurons identified by transgenic expression of enhanced green fluorescence protein (eGFP) possess the ability of regulatory volume decrease (RVD) after hypoosmotic cell swelling. Thus, in the present study, we examined the ability of regulatory volume increase (RVI) after hyperosmotic cell shrinkage in AVP neurons. METHODS: Here, we used eGFP-identified AVP neurons acutely dissociated from AVP-eGFP transgenic rats. We performed single-cell size measurements, cytosolic RT-PCR analysis, AVP secretion measurements, and patch-clamp studies. RESULTS: The AVP neurons were found to respond to a hyperosmotic challenge with physiological cell shrinkage caused by massive secretion of AVP, called a secretory volume decrease (SVD), superimposed onto physical osmotic cell shrinkage, and also to exhibit the ability of RVI coping with osmotic and secretory cell shrinkage. Furthermore, our pharmacological and molecular examinations indicated that AVP secretion and its associated SVD event are triggered by activation of T-type Ca2+ channels, and the RVI event is attained by parallel operation of Na+/H+ exchanger and Cl-/HCO3- anion exchanger. CONCLUSION: Thus, it is concluded that AVP neurons respond to hyperosmotic stimulation with the regulatory volume increase and the secretory volume increase by activating ion transporters and Ca2+ channels, respectively.

Sign in / Sign up

Export Citation Format

Share Document