Cation pump activity and membrane permeability in human senile cataractous lenses

Pasino, Mario; Maraini, G

doi:10.1016/0014-4835(82)90068-9

Cited by 31 publications

(8 citation statements)

References 8 publications

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“…While our study does not directly investigate P2X activation, others have shown that the increased association of P2X 4 with the membrane results in a potentiation of channel current (Toulme et al 2006). Thus, it is possible that diabetes causes an initial cell swelling that induces redistribution of P2X 4 to narrow side membranes, which in turn mediates the membrane depolarization and Ca 2+ inXux observed to accompany the onset of diabetic lens cataract (Crabbe and Goode 1998;Kyselova et al 2004;(Duncan and Bushell 1975;Pasino and Maraini 1982;Duncan et al 1989) and may explain why tissue liquefaction is restricted to a distinct zone in the lens cortex in the rodent model (Bond et al 1996).…”

Section: Discussionmentioning

confidence: 95%

“…The isolation of DF cells causes cell swelling, membrane depolarization, Ca 2+ -inXux, and Wber cell vesiculation (Bhatnagar et al 1995;Wang et al 1997Wang et al , 2001) that can be inhibited by blocking a non-selective cation conductance with the trivalent cation gadolinium . Cortical cataract is associated with membrane depolarization (Duncan and Bushell 1975;Pasino and Maraini 1982;Duncan et al 1989;Crabbe and Goode 1998) and a localized zone of cell swelling in the outer cortex that precedes tissue liquefaction in diabetic cataract (Bond et al 1996). Given that DF cells contain inactive pools of P2X receptors, it is conceivable that their redistribution into the plasma membrane in response to osmotic or hyperglycemic stress may underlie the observed increase in non-selective cation conductance observed under these conditions.…”

Section: Introductionmentioning

confidence: 98%

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Differential membrane redistribution of P2X receptor isoforms in response to osmotic and hyperglycemic stress in the rat lens

Suzuki-Kerr

Lim

Vlajkovic

et al. 2009

Histochem Cell Biol

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P2X(1, 2, 3, 4, 6 and 7) are all expressed in a differentiation-dependent manner in the rat lens. However, in the lens outer cortex the subcellular distribution of all P2X isoforms is predominantly associated with a pool of receptors located in cytoplasmic vesicles. Here we investigate whether osmotic and hyperglycemic stress can alter the subcellular distribution of this cytoplasmic pool of P2X receptors. We show that in a discrete zone of the deeper outer cortex an isoform and stimulus-specific shift in the subcellular distribution of P2X receptors occurs from the cytoplasm to defined membrane domains. In response to hypertonic stress P2X(1) and P2X(4) isoforms became more closely associated with the broad sides of fiber cells, while under hypotonic conditions P2X(4) and P2X(6) isoforms associate with the narrow side membranes. No such changes in subcellular distribution were observed for P2X(2,3 and 7) isoforms. Lens cultured in 50 mM glucose exhibited cell swelling in this zone but only P2X(4) associated with narrow side membranes. Our results indicate P2X receptors can be differentially recruited to specific membrane domains of lens fiber cells by osmotic and hyperglycemic stress. Furthermore they suggest the involvement of specific P2X isoforms in the regulation of fiber cell volume and the initiation of diabetic cataract.

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Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 98%

Differential membrane redistribution of P2X receptor isoforms in response to osmotic and hyperglycemic stress in the rat lens

Suzuki-Kerr

Lim

Vlajkovic

et al. 2009

Histochem Cell Biol

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“…Oxidized disordered lipids in an ordered lipid matrix would be expected to increase the passive permeability of these membranes (39}. An increase in passive permeability is observed during cataractogenesis (40)(41)(42).…”

Section: Resultsmentioning

confidence: 99%

The dual effect of oxidation on lipid bilayer structure

Borchman

Lamba

Salmassi

et al. 1992

Lipids

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Sphingomyelin membranes were prepared with different levels of oxidative damage caused by tert-butyl hydroperoxide (TBH). Temperature-induced changes in membrane hydrocarbon chain packing (phase transitions) were monitored using infrared spectroscopy. Lipid phase transition characteristics were evaluated from thermodynamic parameters fitted to the experimental transition curve data. At temperatures below the lipid phase transition Tc, hydrocarbon chains pack in an ordered state whereas above the Tc the hydrocarbon chains pack in a disordered state. Compared to the non-oxidized control, the packing of the hydrocarbon chains of mildly oxidized sphingomyelin (less than 10 nmol TBH/mg lipid) was no different at all temperatures below the Tc, and was more ordered above the Tc. The hydrocarbon chains of strongly oxidized sphingomyelin (greater than 10 nmol TBH/mg lipid) were more disordered at temperatures above and below the Tc compared to the control samples. These results suggest that lipid oxidation has a dual effect on lipid order. A more ordered or disordered state may result depending on the degree of oxidation and the state of lipid order prior to oxidation. These results could be important for explaining the structural changes in oxidized membranes high in sphingomyelin such as those found in the ocular lens and liver plasma membranes.

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“…16 -21 With age, the increased entry of calcium into clear lenses is offset by an increase in the activity of Ca 2ϩ -ATPase pumps. 22 With cataract, however, lens membrane permeability increases further, [23][24][25][26] total lens calcium is elevated, [1][2][3][4][5][6][7][8][9] and Ca 2ϩ -ATPase activity is decreased by 50%. 27 The Ca 2ϩ -ATPase pump is sensitive to lipid order, 28,29 which changes with age 29 and cataract.…”

mentioning

confidence: 99%

Influence of Age, Diabetes, and Cataract on Calcium, Lipid-Calcium, and Protein-Calcium Relationships in Human Lenses

Tang

Borchman

Yappert

et al. 2003

Invest. Ophthalmol. Vis. Sci.

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The data support the hypothesis that increased intracellular calcium concentrations and a diminished capacity of lens lipids to bind to calcium initiate a cascade of events that culminates in increased light-scattering from lipids and especially proteins. Calcium binding to lipid membranes cannot directly contribute to light-scattering in cataractous lenses. It has been suggested that most of the diffusible calcium in the lens is in the intercellular spaces and that lens lipids in the outer leaflet of the bilayer bind to that calcium. If so, this could account for the 150-fold difference between free and bound calcium levels in the lens.

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Cation pump activity and membrane permeability in human senile cataractous lenses

Cited by 31 publications

References 8 publications

Differential membrane redistribution of P2X receptor isoforms in response to osmotic and hyperglycemic stress in the rat lens

Differential membrane redistribution of P2X receptor isoforms in response to osmotic and hyperglycemic stress in the rat lens

The dual effect of oxidation on lipid bilayer structure

Influence of Age, Diabetes, and Cataract on Calcium, Lipid-Calcium, and Protein-Calcium Relationships in Human Lenses

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