Regulation of cell volume in the perfused rat liver by hormones

The effect of hormones on cell volume was studied in isolated perfused rat liver by assessing the intracellular water space as the difference between a [3H]inulin- and a [14C]urea-accessible space. The intracellular water space (control value 559 +/- 7 microliters/g of liver; n = 88) increased on addition of insulin (35 nM) or phenylephrine (5 microM) by 12 or 8% respectively, whereas it decreased with cyclic AMP (cAMP; 50 microM), glucagon (100 nM) or adenosine (50 microM) by 9, 13 or 6% respectively. Both insulin and glucagon exerted half-maximal effects on cell volume and cellular K+ balance at hormone concentrations found physiologically in the portal vein. Adenosine-induced cell shrinkage was explained by a net K+ release from the liver. Phenylephrine (5 microM) led to cell swelling by about 8%, which was additive to insulin-induced swelling. Extracellular ATP (20 microM) induced cell shrinkage by about 6%; this was additive to adenosine-induced shrinkage. Vasopressin (15 nM) did not appreciably change cell volume, but induced marked cell shrinkage when glucagon or cAMP was present. Insulin- and phenylephrine-induced cell swelling was counteracted by cAMP. Hormone-induced changes of intracellular water space could sufficiently explain accompanying liver mass changes induced by glucagon, cAMP, adenosine or vasopressin, but not those by phenylephrine and extracellular ATP. The data show that liver cell volume is subject to hormonal regulation, in part owing to modification of cellular K+ balance. Glucagon- and insulin-induced cell volume changes occur already in the presence of physiological hormone concentrations. The effects of Ca2(+)-mobilizing hormones on cell volume are not uniform. In view of the recently established role of cell volume changes in modulating liver cell function, the present findings open a new perspective on the mechanisms of hormone action in liver, underlining our previous hypothesis that cell volume changes may represent a ‘second messenger’ of hormone action.

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Regulation of liver cell volume and proteolysis by glucagon and insulin

Biochemical Journal ◽

10.1042/bj2780771 ◽

1991 ◽

Vol 278 (3) ◽

pp. 771-777 ◽

Cited By ~ 51

Author(s):

S Vom Dahl ◽

C Hallbrucker ◽

F Lang ◽

W Gerok ◽

D Häussinger

Keyword(s):

Cell Volume ◽

Liver Cell ◽

Intracellular Water ◽

Cell Swelling ◽

Isolated Perfused Rat Liver ◽

Cell Shrinkage ◽

Glucagon And Insulin ◽

Opposing Effects ◽

Water Space

The effects of insulin and glucagon on liver cell volume and proteolysis were studied in isolated perfused rat liver. The rate of proteolysis was assessed as [3H]leucine release from single-pass-perfused livers from rats which had been prelabelled in vivo by intraperitoneal injection of [3H]leucine. The intracellular water space was determined from the wash-out profiles of simultaneously added [3H]inulin and [14C]urea. In normo-osmotic (305 mosM) control perfusions the intracellular water space was 548 +/- 10 microliters/g wet mass (n = 44) and was increased by 16.5 +/- 2.6% (n = 6), i.e. by 85 +/- 14 microliters/g, after hypoosmotic exposure (225 mosM). Glucagon (0.1 microM) decreased the intracellular water space by 17 +/- 4% (n = 4), whereas insulin (35 nM) increased the intracellular water space by 9.3 +/- 1.4% (n = 15). Also, in isolated rat hepatocyte suspensions insulin (100 nM) caused cell swelling by 10.7 +/- 1.8% (n = 16), which was fully reversed by glucagon. In perfused liver, insulin-induced cell swelling was accompanied by a hepatic net K+ uptake (4.5 +/- 0.2 mumol/g) and an inhibition of proteolysis by 21 +/- 2% (n = 12); further addition of glucagon led to a net K+ release of 3.8 +/- 0.2 mumol/g (n = 7) and fully reversed the insulin effects on both cell volume and proteolysis. Similarly, insulin-induced cell swelling and inhibition of proteolysis were completely antagonized by hyperosmotic (385 mosM) cell shrinkage. Furthermore, cell swelling and inhibition of proteolysis after hypo-osmotic exposure or amino acid addition were reversed by glucagon-induced cell shrinkage. There was a close relationship between the extent of cell swelling and the inhibition of proteolysis, regardless of whether cell volume was modified by insulin, glucagon or aniso-osmotic exposure. The data show that glucagon and insulin are potent modulators of liver cell volume, at least in part by alterations of cellular K+ balance, and that their opposing effects on hepatic proteolysis can largely be explained by opposing effects on cell volume. It is hypothesized that hormone-induced alterations of cell volume may represent an important, not yet recognized, mechanism mediating hormonal effects on metabolism.

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Cell swelling increases bile flow and taurocholate excretion into bile in isolated perfused rat liver

Biochemical Journal ◽

10.1042/bj2810593 ◽

1992 ◽

Vol 281 (3) ◽

pp. 593-595 ◽

Cited By ~ 23

Author(s):

C Hallbrucker ◽

F Lang ◽

W Gerok ◽

D Häussinger

Keyword(s):

Bile Acid ◽

Amino Acid ◽

Cell Volume ◽

Rat Liver ◽

Bile Flow ◽

Cell Swelling ◽

Isolated Perfused Rat Liver ◽

Perfused Rat Liver ◽

Volume Changes ◽

Close Relationship

The effects of aniso-osmotically and amino-acid-induced cell-volume changes on bile flow and biliary taurocholate excretion were studied in isolated perfused rat liver. With taurocholate (100 microM) in the influent perfusate, hypo-osmotic exposure (225 mosmol/l) increased taurocholate excretion into bile and bile flow by 42 and 27% respectively, whereas inhibition by 32 and 47% respectively was observed after hyperosmotic (385 mosmol/l) exposure. The effects of aniso-moticity on taurocholate excretion into bile was observed throughout aniso-osmotic exposure, even after completion of volume-regulatory ion fluxes and were fully reversible upon re-exposure to normo-osmotic media. Hypo-osmotic cell swelling (225 mosmol/l) increased the Vmax. of taurocholate translocation from the sinusoidal compartment into bile about 2-fold. Also, cell swelling induced by glutamine and glycine stimulated both bile flow and biliary taurocholate excretion. There was a close relationship between the aniso-osmotically and amino-acid-induced change of cell volume and taurocholate excretion into bile. The data suggest that liver cell volume plays an important role in regulating bile-acid-dependent bile flow and biliary taurocholate excretion.

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Cell volume and bile acid excretion

Biochemical Journal ◽

10.1042/bj2880681 ◽

1992 ◽

Vol 288 (2) ◽

pp. 681-689 ◽

Cited By ~ 71

Author(s):

D Häussinger ◽

C Hallbrucker ◽

N Saha ◽

F Lang ◽

W Gerok

Keyword(s):

Amino Acids ◽

Cell Volume ◽

Liver Cell ◽

Bile Flow ◽

Cell Swelling ◽

Isolated Perfused Rat Liver ◽

Cell Shrinkage ◽

Volume Changes ◽

Close Relationship ◽

Stimulation Of

The interaction between cell volume and taurocholate excretion into bile was studied in isolated perfused rat liver. Cell swelling due to hypo-osmotic exposure, addition of amino acids or insulin stimulated taurocholate excretion into bile and bile flow, whereas hyperosmotic cell shrinkage inhibited these. These effects were explained by changes in Vmax of taurocholate excretion into bile: Vmax. increased from about 300 to 700 nmol/min per g after cell swelling by 12-15% caused by either hypo-osmotic exposure or addition of amino acids under normo-osmotic conditions. Steady-state taurocholate excretion into bile was not affected when the influent K+ concentration was increased from 6 to 46 mM or decreased to 1 mM with iso-osmoticity being maintained by corresponding changes in the influent Na+ concentration. Replacement of 40 mM-NaCl by 80 mM-sucrose decreased taurocholate excretion into bile by about 70%; subsequent hypo-osmotic exposure by omission of sucrose increased taurocholate excretion to 160%. Only minor, statistically insignificant, effects of aniso-osmotic cell volume changes on the appearance of bolus-injected horseradish peroxidase in bile were observed. Taurocholate (400 microM) exhibited a cholestatic effect during hyperosmotic cell shrinkage, but not during hypo-osmotic cell swelling. Both taurocholate and tauroursodeoxycholate increased liver cell volume. Tauroursodeoxycholate stimulated taurocholate (100 microM) excretion into bile. This stimulatory effect was strongly dependent on the extent of tauroursodeoxycholate-induced cell swelling. During continuous infusion of taurocholate (100 microM) further addition of tauroursodeoxycholate at concentrations of 20, 50 and 100 microM increased cell volume by 10, 8 and 2% respectively, in parallel with a stimulation of taurocholate excretion into bile by 29, 27 and 9% respectively. There was a close relationship between the extent of cell volume changes and taurocholate excretion into bile, regardless of whether cell volume was modified by tauroursodeoxycholate, amino acids or aniso-osmotic exposure. The data suggest that: (i) liver cell volume is one important factor determining bile flow and biliary taurocholate excretion; (ii) swelling-induced stimulation of taurocholate excretion into bile is probably not explained by alterations of the membrane potential; (iii) bile acids modulate liver cell volume; (iv) taurocholate-induced cholestasis may depend on cell volume; (v) stimulation of taurocholate excretion into bile by tauroursodeoxycholate can largely be explained by tauroursodeoxycholate-induced cell swelling.

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Inhibition of proteolysis by cell swelling in the liver requires intact microtubular structures

Biochemical Journal ◽

10.1042/bj3080529 ◽

1995 ◽

Vol 308 (2) ◽

pp. 529-536 ◽

Cited By ~ 27

Author(s):

S vom Dahl ◽

B Stoll ◽

W Gerok ◽

D Häussinger

Keyword(s):

Cell Volume ◽

Rat Liver ◽

Rat Hepatocytes ◽

Isolated Hepatocytes ◽

Cell Swelling ◽

Perfused Rat Liver ◽

Volume Changes ◽

Isolated Rat Hepatocytes ◽

Microtubule Inhibitors ◽

Microtubular Structures

In the perfused rat liver, proteolysis is inhibited by cell swelling in response to hypo-osmotic media, glutamine and insulin. Colchicine, an inhibitor of microtubules, did not affect cell swelling in response to these agonists. However, the antiproteolytic action of these effectors was largely blunted in the presence of colchicine or the microtubule inhibitors colcemid and taxol. On the other hand, inhibition of proteolysis by phenylalanine, asparagine or NH4Cl, i.e. compounds which exert their antiproteolytic effects by mechanisms distinct from cell swelling, was not sensitive to colchicine. Swelling-induced inhibition of proteolysis was not affected by cytochalasin B. The anti-proteolytic effect of hypo-osmotic cell swelling and insulin was largely abolished in freshly isolated rat hepatocytes; however, it reappeared upon cultivation of the hepatocytes for 6-10 h. The restoration of the sensitivity of proteolysis to cell volume changes was accompanied by a progressive reorganization of microtubule structures, as shown by immunohistochemical staining for tubulin. It is concluded that intact microtubules are required for the control of proteolysis by cell volume, but not for the control of proteolysis by phenylalanine, asparagine or NH4Cl. These findings may explain why others [Meijer, Gustafson, Luiken, Blommaart, Caro, Van Woerkom, Spronk and Boon (1993) Eur. J. Biochem. 215, 449-454] failed to detect an antiproteolytic effect of hypo-osmotic exposure of freshly isolated hepatocytes. This effect, however, which is consistently found in the intact perfused rat liver, also reappeared in isolated hepatocytes when they were allowed to reorganize their microtubular structures in culture.

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Liver cell swelling leads to upregulation of miR-141-3p in perfused rat liver and primary rat hepatocytes

10.1055/s-0040-1721965 ◽

2021 ◽

Author(s):

N Bardeck ◽

M Paluschinski ◽

M Castoldi ◽

T Luedde ◽

D Häussinger ◽

...

Keyword(s):

Rat Liver ◽

Liver Cell ◽

Rat Hepatocytes ◽

Cell Swelling ◽

Perfused Rat Liver ◽

Primary Rat Hepatocytes

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Cell swelling inhibits proteolysis in perfused rat liver

Biochemical Journal ◽

10.1042/bj2720239 ◽

1990 ◽

Vol 272 (1) ◽

pp. 239-242 ◽

Cited By ~ 67

Author(s):

D Häussinger ◽

C Hallbrucker ◽

S vom Dahl ◽

F Lang ◽

W Gerok

Keyword(s):

Amino Acids ◽

Rat Liver ◽

Liver Cell ◽

Intraperitoneal Injection ◽

Branched Chain Amino Acids ◽

Cell Swelling ◽

Perfused Rat Liver ◽

Close Relationship ◽

Branched Chain

Exposure of isolated single-pass-perfused rat liver to hypo-osmotic media resulted in liver cell swelling and an inhibition of release of branched-chain amino acids. Similarly, cell swelling inhibited [3H]leucine release from perfused livers from rats in which liver proteins were prelabelled in vivo by intraperitoneal injection of L-[4,5-3H]leucine 16-20 h before the experiment. The effects of cell swelling on [3H]leucine release were fully reversible. [3H]Leucine release was also inhibited when cell swelling was induced by addition of glutamine (0.5-2 mM). There was a close relationship between the inhibition of [3H]leucine release and the degree of liver cell swelling, regardless of whether cell swelling was induced by hypo-osmotic perfusion or addition of glutamine. The data suggest that the known anti-proteolytic effect of glutamine is in large part due to glutamine-induced hepatocyte swelling.

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Liver cell hydration and integrin signaling

Biological Chemistry ◽

10.1515/hsz-2021-0193 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Michele Bonus ◽

Dieter Häussinger ◽

Holger Gohlke

Keyword(s):

Cell Volume ◽

Liver Cell ◽

Cell Function ◽

The Other ◽

Signaling Cascades ◽

Integrin Signaling ◽

Volume Changes ◽

The One ◽

And Oxidative Stress

Abstract Liver cell hydration (cell volume) is dynamic and can change within minutes under the influence of hormones, nutrients, and oxidative stress. Such volume changes were identified as a novel and important modulator of cell function. It provides an early example for the interaction between a physical parameter (cell volume) on the one hand and metabolism, transport, and gene expression on the other. Such events involve mechanotransduction (osmosensing) which triggers signaling cascades towards liver function (osmosignaling). This article reviews our own work on this topic with emphasis on the role of β1 integrins as (osmo-)mechanosensors in the liver, but also on their role in bile acid signaling.

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Regulation of cell function by the cellular hydration state

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1994.267.3.e343 ◽

1994 ◽

Vol 267 (3) ◽

pp. E343-E355 ◽

Cited By ~ 27

Author(s):

D. Haussinger ◽

F. Lang ◽

W. Gerok

Keyword(s):

Cell Volume ◽

Cell Function ◽

Narrow Range ◽

Cell Swelling ◽

Metabolic Function ◽

Cell Shrinkage ◽

Short Term ◽

Hydration State ◽

Per Se ◽

And Oxidative Stress

Cellular hydration can change within minutes under the influence of hormones, nutrients, and oxidative stress. Such short-term modulation of cell volume within a narrow range acts per se as a potent signal which modifies cellular metabolism and gene expression. It appears that cell swelling and cell shrinkage lead to certain opposite patterns of cellular metabolic function. Apparently, hormones and amino acids can trigger those patterns simply by altering cell volume. Thus alterations of cellular hydration may represent another important mechanism for metabolic control and act as another second or third messenger linking cell function to hormonal and environmental alterations.

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Volume-sensitive Ca influx and release from intracellular pools in gastric parietal cells

AJP Cell Physiology ◽

10.1152/ajpcell.1992.263.3.c584 ◽

1992 ◽

Vol 263 (3) ◽

pp. C584-C589 ◽

Cited By ~ 32

Author(s):

P. A. Negulescu ◽

B. Munck ◽

T. E. Machen

Keyword(s):

Image Processing ◽

Cell Volume ◽

Digital Image Processing ◽

Parietal Cells ◽

Cell Swelling ◽

Cell Shrinkage ◽

Gastric Glands ◽

Intact Rabbit ◽

Induced Changes ◽

Gastric Parietal Cells

The effects of osmotically induced changes in cell volume on cytoplasmic free Ca (Cai) were studied in parietal cells from intact rabbit gastric glands using digital image processing of fura-2 fluorescence. In resting unstimulated cells, Cai was unaffected by either cell swelling or shrinking when osmolarity was varied between 200 and 400 mosM (isotonicity 290 mosM). However, when cells were swelled in a 165 mosM solution (55% tonicity), a biphasic Ca increased was observed. On average, Cai increased transiently from 80 to 218 nM before stabilizing at approximately 140 nM. The peak was due to release from intracellular pools because it was present in Ca-free solutions while the sustained elevation was dependent on external Ca. In carbachol-stimulated cells, Ca influx was most sensitive to cell shrinkage. For example, addition of 25 mM sucrose (108% tonicity) caused a 30% decrease in the sustained carbachol-stimulated Cai increase (plateau). In contrast, carbachol-stimulated cells were relatively insensitive to cell swelling, with a 30% decrease in tonicity causing only a 15% increase in the plateau. However, as in the unstimulated cells, extreme (55% tonicity) swelling caused additional increases in Cai levels. The carbachol-dependent effects of changes in cell volume on Cai could be mimicked by treating cells with thapsigargin, an inhibitor of Ca pumps of intracellular membranes that also has been shown to stimulate Ca entry. Thus, although extreme swelling conditions (55% tonicity) could elicit Cai increases in either the presence or absence of agonist, agonist was required to observe Cai decreases due to cell shrinkage.(ABSTRACT TRUNCATED AT 250 WORDS)

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