Effect of barium on cell volume regulation in rabbit proximal straight tubules

Welling, Paul A.; Linshaw, Michael A.; Sullivan, Lawrence P.

doi:10.1152/ajprenal.1985.249.1.f20

Cited by 39 publications

(30 citation statements)

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“…The change in cell volume on return to isotonic medium gives evidence that during isovolumetric regulation solutes were removed from (hypotonic) or added to (hypertonic) intracellular fluid. The identity of the solutes is not revealed by the current study, but previous work suggests that in hypotonic media Na, K, and C1 are probably lost from the cytoplasm (2,6). Volume regulation in hypertonic media was not observed previously in isolated proximal tubules, so there is little basis to speculate on the identity ofsolutes added to the cells during hypertonic isovolumetric regulation.…”

Section: Discussioncontrasting

confidence: 77%

“…In previous studies, proximal tubules cells exposed suddenly to hypotonic media did not return cell volume to control levels (1)(2)(3)(4)(5)(6). This incomplete volume regulatory behavior in vitro is typical of other types of cells as well (35,36).…”

Section: Discussionmentioning

confidence: 81%

“…When returned to isotonic medium, tubule volume decreased below the initial isotonic baseline, which reflects a net loss of intracellular solute during the VRD phase. K+ and Na' are the major intracellular cations lost during the VRD phase (2), and a recent report indicates that chloride may be the principal anion accompanying the cations (6).…”

Section: Resultsmentioning

confidence: 99%

“…Studies of volume regulatory mechanisms in mammalian kidneys have principally used nonperfused tubule segments studied in vitro (1)(2)(3)(4)(5)(6)(7)(8). In this nonpolar preparation, volume regulation primarily reflects the steady-state transport of solutes and water across basolateral membranes (2,3).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies ofrenal volume regulation have used tissue slices, cell suspensions, isolated tubules, and single cells (1)(2)(3)(4)(5)(6)(7)(8)(22)(23)(24)(25)(26)(27)(28)(29)(30). In all of these studies the medium osmolality was changed suddenly, which is uncharacteristic of osmotic changes that might be encountered in pathophysiologic states in vivo.…”

Section: Introductionmentioning

confidence: 99%

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Isovolumetric regulation of isolated S2 proximal tubules in anisotonic media.

Lohr¹,

Grantham²

1986

J. Clin. Invest.

124

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Sudden alteration in medium osmolality causes an osmometric change in proximal tubule cell size followed by restoration of cell volume toward normal in hypotonic but not in hypertonic medium. We determined the capability of isolated nonperfused proximal tubules to prevent a change in cell volume in anisotonic media. The external osmolality was gradually changed over a range from 110 to 480 mosM. At 1.5 mosM/min, cell volume remained constant between 167±9 and 361±7 mosM, a phenomenon termed isovolumetric regulation (IVR). Cells lost intracellular solutes in hypotonic and gained intracellular solutes in hypertonic media. Raffinose or choline chloride substitution showed that osmolality, rather than NaCG, signalled cell volume maintenance in hyperosmotic media. Cooling (7-100C) blocked IVR. IVR was maintained when osmolality was lowered at a rate of 27, but not at 42 mosM/min. IVR was not observed when the rate of osmolality increase exceeded 3 mosM/min. We conclude that proximal tubule cells sensitively regulate intracellular volume in an osmolality range of pathophysiologic interest by mechanisms dependent on (a) the rate of net water movement across basolateral membranes and (b) the absolute intracellular content of critical solutes.

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Section: Discussioncontrasting

confidence: 77%

Section: Discussionmentioning

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Isovolumetric regulation of isolated S2 proximal tubules in anisotonic media.

Lohr¹,

Grantham²

1986

J. Clin. Invest.

124

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Role of actin filament organization in cell volume and ion channel regulation

Cantiello

1997

J. Exp. Zool.

113

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The actin cytoskeleton is an intracellular structure, which is involved in the onset and control of cell shape and function. In order for this relevant network to control its own and thus cell volume, specific interactions between the actin cytoskeleton and ion channel regulation controlling intracellular salt and water homeostasis may be invoked. The hypotonic shock‐induced, cell volume regulatory decrease (RVD) of most eukaryotic cells is a particularly useful example, as it is initiated and regulated by concerted processes involving both adaptive changes in actin filament organization and bulk fluid extrusion triggered by saline movement and the consequent decrease in cell water. The onset of RVD is linked to the selective activation of osmotically‐sensitive ion channels and other relevant ion transport mechanisms involved in the net ionic movement from the cytosol. Such regulatory processes, entailing effector changes in actin filament organization which target the plasma membrane, are largely unknown. In this report, recent studies are summarized implicating dynamic changes in gel properties of the actin cytoskeleton as the effector mechanism in the regulation of ion channel activity, and thus cell volume, in human melanoma cells. Based on the characterization of the hypotonic cell volume regulatory response of human melanoma cells devoid of a functional actin‐binding protein (ABP‐280, a filamin homolog) and their genetically rescued counterpart transfected with a functional ABP, a hypothesis is raised which is consistent with a regulatory “sensory” mechanism based on the ability of actin networks to respond to changes in the intracellular water‐salt homeostasis, which in turn effects signals controlling membrane function, including ion channel activity. J. Exp. Zool. 279:425–435, 1997. © 1997 Wiley‐Liss, Inc.

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Activation of K+ and Cl? channels in MDCK cells during volume regulation in hypotonic media

Banderali

Roy

1992

J. Membarin Biol.

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Single-channel patch-clamp experiments were performed on MDCK cells in order to characterize the ionic channels participating in regulatory volume decrease (RVD). Subconfluent layers of cultured cells were exposed to a hypotonic medium (150 mOsm), and the membrane currents at the single-channel level were measured in cell-attached experiments. The results indicate that MDCK cells respond to a hypotonic swelling by activating several different ionic conductances. In particular, a potassium and a chloride channel appeared in the recordings more frequently than other channels, and this allowed a more detailed study of their properties in the inside-out configuration of the patch-clamp technique. The potassium channel had a linear I/V curve with a unitary conductance of 24 +/- 4 pS in symmetrical K+ concentrations (145 mM). It was highly selective for K+ ions vs. Na+ ions: PNa/PK less than 0.04. The time course of its open probability (P0) showed that the cells responded to the hypotonic shock with a rapid activation of this channel. This state of high activity was maintained during the first minute of hypotonicity. The chloride channel participating in RVD was an outward-rectifying channel: outward slope conductance of 63.3 +/- 4.7 pS and inward slope conductance of 26.1 +/- 4.9 pS. It was permeable to both Cl- and NO3- and its maximal activation after the hypotonic shock was reached after several seconds (between 30 and 100 sec). The activity of this anionic channel did not depend on cytoplasmic calcium concentration. Quinine acted as a rapid blocker of both channels when applied to the cytoplasmic side of the membrane. In both cases, 1 mM quinine reversibly reduced single-channel current amplitudes by 20 to 30%. These results indicate that MDCK cells responded to a hypotonic swelling by an early activation of highly selective potassium conductances and a delayed activation of anionic conductances. These data are in good agreement with the changes of membrane potential measured during RVD.

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Effect of barium on cell volume regulation in rabbit proximal straight tubules

Cited by 39 publications

References 0 publications

Isovolumetric regulation of isolated S2 proximal tubules in anisotonic media.

Isovolumetric regulation of isolated S2 proximal tubules in anisotonic media.

Role of actin filament organization in cell volume and ion channel regulation

Activation of K+ and Cl? channels in MDCK cells during volume regulation in hypotonic media

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