Unusual permeability properties of gastric gland cells

Waisbren, Steven; Geibel, John P.; Modlin, Irvin M.; Boron, Walter F.

doi:10.1038/368332a0

Cited by 156 publications

(133 citation statements)

References 15 publications

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“…Bar = 100 microns experimentation as reviewed by Endeward et al (2014). Approximately 2 decades 269 ago, research using a single stomach gland demonstrated that while CO2 was 270 transported across basal membranes as rapidly as might be predicted by the theory of 271 "free movement," transport across the apical membrane (Waisbren et al 1994) was 272 at least two orders of magnitude slower. Similarly, Endeward and Gros (2013) 273 demonstrated that CO2 permeability for guinea pig colon membrane is more than 100 274 times slower than CO2 permeability for human red cells.…”

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confidence: 99%

Mitonucleons formed during differentiation of Ishikawa endometrial cells generate vacuoles that elevate monolayer syncytia: Differentiation of Ishikawa domes, Part 1

Fleming

2016

Preprint

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In 1998, we published a paper (Fleming et.al, 1998) describing some aspects of Ishikawa endometrial epithelial cell differentiation from monolayer cells into cells forming fluid-filled hemispheres called domes. The process begins with the dissolution of membranes within discrete regions of the monolayer. Nuclei from fused cells aggregate and endogenous biotin in particulate structures assumed to be mitochondria increase throughout the resulting syncytium. Endogenous biotin is also the distinguishing feature of a membrane that surrounds aggregates of multiple nuclei in a structure called a mitonucleon. The current paper includes additional observations on structural changes accompanying Ishikawa differentiation. Vacuoles form in the heterochromatin of the mitonucleon and within the biotin-containing double membrane surrounding heterochromatin. With the formation of vacuoles, the mitonucleon can be seen to rise along with the apical membrane of the syncytium in which it formed. The small vacuoles that form within the heterochromatin result in structures similar to “cells with optically clear nuclei” found in some cancers. The second larger vacuole that forms within the membrane surrounding the heterochromatin transforms the cell profile to one that resembles “signet ring” cells also observed in some cancers. Eventually the membrane surrounding the massed heterochromatin, generated three to four hours earlier, is breached and previously aggregated nuclei disaggregate. During this process heterochromatin in the mitonucleons undergoes changes usually ascribed to cells undergoing programmed cell death such as pyknosis and DNA fragmentation (Fleming, 2016b). The cells do not die, instead chromatin filaments appear to coalesce into a chromatin mass that gives rise to dome-filling nuclei by amitosis during the final three to four hours of the 20 hour differentiation (Fleming, 2016c).

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confidence: 99%

Mitonucleons formed during differentiation of Ishikawa endometrial cells generate vacuoles that elevate monolayer syncytia: Differentiation of Ishikawa domes, Part 1

Fleming

2016

Preprint

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“…pH i was measured with the fluorescent dye BCECF and a digital imaging system. Data from reference (24). Ϫ by using active-transport processes to secrete H ϩ into the tubule lumen and titrating HCO 3 Ϫ to CO 2 and H 2 O.…”

Section: Membranes With Negligible Gas Permeabilitymentioning

confidence: 99%

Acid-Base Transport by the Renal Proximal Tubule

Boron

2006

Journal of the American Society of Nephrology

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170

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One of the major tasks of the renal proximal tubule is to secrete acid into the tubule lumen, thereby reabsorbing approximately 80% of the filtered HCO 3 ؊ as well as generating new HCO 3 ؊ for regulating blood pH. This review summarizes the cellular and molecular events that underlie four major processes in HCO 3 ؊ reabsorption. The first is CO 2 entry across the apical membrane, which in large part occurs via a gas channel (aquaporin 1) and acidifies the cell. The second process is apical H ؉ secretion via Na-H exchange and H ؉ pumping, processes that can be studied using the NH 4 ؉ prepulse technique. The third process is the basolateral exit of HCO 3 ؊ via the electrogenic Na/HCO 3 co-transporter, which is the subject of at least 10 mutations that cause severe proximal renal tubule acidosis in humans. The final process is the regulation of overall HCO 3 ؊ reabsorption by CO 2 and HCO 3 ؊ sensors at the basolateral membrane. Together, these processes ensure that the proximal tubule responds appropriately to acute acid-base disturbances and thereby contributes to the regulation of blood pH.

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“…Gross movement of O 2 and CO 2 across the lung has been measured, as has NH 3 permeability of some membranes (5)(6)(7). Although it has been accepted that gases are freely permeable across membranes, rapid flux of gases across some membranes would upset carefully regulated electrolyte concentrations.…”

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confidence: 99%

Reconstituted Aquaporin 1 Water Channels Transport CO2 across Membranes

Prasad

Coury

Finn

et al. 1998

Journal of Biological Chemistry

160

127

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Biological membranes provide selective barriers to a number of molecules and gases. However, the factors that affect permeability to gases remain unclear because of the difficulty of accurately measuring gas movements. To determine the roles of lipid composition and the aquaporin 1 (AQP1) water channel in altering CO 2 flux across membranes, we developed a fluorometric assay to measure CO 2 entry into vesicles. Maximal CO 2 flux was ϳ1000-fold above control values with 0.5 mg/ml carbonic anhydrase. Unilamellar phospholipid vesicles of varying composition gave widely varying water permeabilities but similar CO 2 permeabilities at 25°C. When AQP1 purified from human red blood cells was reconstituted into proteoliposomes, however, it increased water and CO 2 permeabilities markedly. Both increases were abolished with HgCl 2 , and the mercurial inhibition was reversible with ␤-mercaptoethanol. We conclude that unlike water and small nonelectrolytes, CO 2 permeation is not significantly altered by lipid bilayer composition or fluidity. AQP1 clearly serves to increase CO 2 permeation, likely through the water pore; under certain circumstances, gas permeation through membranes is protein-mediated.

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Unusual permeability properties of gastric gland cells

Cited by 156 publications

References 15 publications

Mitonucleons formed during differentiation of Ishikawa endometrial cells generate vacuoles that elevate monolayer syncytia: Differentiation of Ishikawa domes, Part 1

Mitonucleons formed during differentiation of Ishikawa endometrial cells generate vacuoles that elevate monolayer syncytia: Differentiation of Ishikawa domes, Part 1

Acid-Base Transport by the Renal Proximal Tubule

Reconstituted Aquaporin 1 Water Channels Transport CO2 across Membranes

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