scholarly journals Localization of Hydrogen Ion and Chloride Ion Fluxes in Nitella

1969 ◽  
Vol 54 (3) ◽  
pp. 397-414 ◽  
Author(s):  
Donald G. Spear ◽  
June K. Barr ◽  
C. E. Barr
Keyword(s):  
Ion Transport ◽  
Chloride Ion ◽  
Ion Fluxes ◽  
Hydrogen Ion ◽  
Transport Mechanisms ◽  
Active Efflux ◽  
Ion Movement ◽  
Acid And Base ◽  
Base Formation ◽  
Chloride Influx

Alternating bands of acid and base formation have been detected along the length of the internodal cell of Nitella clavata when it is illuminated, while in the dark this phenomenon is minimal. Chloride influx occurs only or largely in the acid-extruding regions, and this is also a light-dependent ion movement. Chloride efflux is slightly dependent on illumination and is not localized as are H+ efflux and Cl- influx. The results obtained support Kitasato's (1968) proposal that a large passive H+ influx is balanced by an active efflux of this ion. Transport mechanisms suggested by the correlations of Cl- and HCO3- influxes with H+ extrusion are discussed.

Simulation of chloride ion transport in concrete under the coupled effects of a bending load and drying–wetting cycles

2020 ◽  
Vol 241 ◽  
pp. 118045 ◽  
Author(s):  
Cao Tongning ◽  
Zhang Lijuan ◽  
Sun Guowen ◽  
Wang Caihui ◽  
Zhang Ying ◽  
...  
Keyword(s):  
Ion Transport ◽  
Chloride Ion ◽  
Bending Load ◽  
Chloride Ion Transport

scholarly journals Ion Transport and the Development of Hydrogen Ion Secretion in the Stomach of the Metamorphosing Bullfrog Tadpole

1969 ◽  
Vol 54 (1) ◽  
pp. 76-95 ◽  
Author(s):  
John G. Forte ◽  
Liangchai Limlomwongse ◽  
Dinkar K. Kasbekar
Keyword(s):  
Ion Transport ◽  
Active Transport ◽  
Hydrogen Ion ◽  
Equilibrium Potential ◽  
Flux Analysis ◽  
Cell Interior ◽  
Ion Secretion ◽  
Hcl Secretion ◽  
Bullfrog Tadpole ◽  
Induced Changes

Isolated bullfrog tadpole stomachs secrete H+ by stage XXIV of metamorphosis, when tail reabsorption is nearly complete. At this stage the PD shows characteristic responses identical to those of the adult. The appearance of HCl secretion correlates well with other studies showing the morphogenesis of oxyntic cells. Prior to the development of H+ secretion tadpole stomachs maintain a PD similar in polarity and magnitude to that of the adult; i.e., secretory (S) side negative with respect to the nutrient (N) side. The interdependence with aerobic metabolism appeared to increase progressively through metamorphosis; however, glycolytic inhibitors always abolished the PD. Isotopic flux analysis showed that the transepithelial movement of Na+ was consistent with passive diffusion, whereas an active transport of Cl- from N to S was clearly indicated. Variations in [Na+], [K+], and [Cl-] in the bathing solutions induced changes consistent with the following functional description of the pre-H+-secreting tadpole stomach. (a) The S side is relatively permeable to Cl-, but not to Na+ or K+. (b) An equilibrium potential for K+ and Cl- exists at the N interface. (c) Ouabain abolishes the selective K+ permeablity at the N interface and reduces the total PD. (d) Effects of Na+ replacement by choline in the N solution become manifest only below 10–20 mM. It is concluded that prior to development of H+ secretion, the tadpole gastric PD is generated by a Cl- pump from N to S and a Na+ pump operating from the cell interior toward the N side.

The anterior and posterior ‘stomach’ regions of larval Aedes aegypti midgut: regional specialization of ion transport and stimulation by 5-hydroxytryptamine

1999 ◽  
Vol 202 (3) ◽  
pp. 247-252 ◽  
Author(s):  
T.M. Clark ◽  
A. Koch ◽  
D.F. Moffett
Keyword(s):  
Steady State ◽  
Aedes Aegypti ◽  
Ion Transport ◽  
Malpighian Tubules ◽  
Transport Mechanisms ◽  
Regional Specialization ◽  
Negative Deflection ◽  
Electrical Polarity

The ‘stomach’ region of the larval mosquito midgut is divided into histologically distinct anterior and posterior regions. Anterior stomach perfused symmetrically with saline in vitro had an initial transepithelial potential (TEP) of −66 mV (lumen negative) that decayed within 10–15 min to a steady-state TEP near −10 mV that was maintained for at least 1 h. Lumen-positive TEPs were never observed in the anterior stomach. The initial TEP of the perfused posterior stomach was opposite in polarity, but similar in magnitude, to that of the anterior stomach, measuring +75 mV (lumen positive). This initial TEP of the posterior stomach decayed rapidly at first, then more slowly, eventually reversing the electrical polarity of the epithelium as lumen-negative TEPs were recorded in all preparations within 70 min. Nanomolar concentrations of the biogenic amine 5-hydroxytryptamine (5-HT, serotonin) stimulated both regions, causing a negative deflection of the TEP of the anterior stomach and a positive deflection of the TEP of the posterior stomach. Phorbol 12,13-diacetate also caused a negative deflection of the TEP of the anterior stomach, but had no effect on the TEP of the posterior stomach. These data demonstrate that 5-HT stimulates region-specific ion-transport mechanisms in the stomach of Aedes aegypti and suggest that 5-HT coordinates the actions of the Malpighian tubules and midgut in the maintenance of an appropriate hemolymph composition in vivo.

scholarly journals More actors in ammonia absorption by the thick ascending limb

2012 ◽  
Vol 302 (3) ◽  
pp. F293-F297 ◽  
Author(s):  
Pascal Houillier ◽  
Soline Bourgeois
Keyword(s):  
Current Knowledge ◽  
Collecting Duct ◽  
Ammonia Excretion ◽  
Hydrogen Ion ◽  
Thick Ascending Limb ◽  
Loop Of Henle ◽  
Transport Mechanisms ◽  
Sodium Hydrogen ◽  
Ammonia Transport ◽  
Ammonia Absorption

This review will briefly summarize current knowledge on the basolateral ammonia transport mechanisms in the thick ascending limb (TAL) of the loop of Henle. This segment transports ammonia against a concentration gradient and is responsible for the accumulation of ammonia in the medullary interstitium, which, in turn, favors ammonia secretion across the collecting duct. Experimental data indicate that the sodium/hydrogen ion exchanger isoform 4 (NHE4; Scl9a4) is a sodium/ammonia exchanger and plays a major role in this process. Disruption of murine NHE4 leads to metabolic acidosis with inappropriate urinary ammonia excretion and decreases the ability of the TAL to absorb ammonia and to build the corticopapillary ammonia gradient. However, NHE4 does not account for the entirety of ammonia absorption by the TAL, indicating that, at least, one more transporter is involved.

scholarly journals Molecular Dynamics Study of Ion Transport in Polymer Electrolytes of All-Solid-State Li-Ion Batteries

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1012
Author(s):  
Takuya Mabuchi ◽  
Koki Nakajima ◽  
Takashi Tokumasu
Keyword(s):  
Molecular Dynamics ◽  
Solid State ◽  
Ion Transport ◽  
Polyethylene Oxide ◽  
Polymer Electrolytes ◽  
Li Ion Batteries ◽  
Transport Mechanisms ◽  
Li Ion ◽  
Dynamics Simulations ◽  
The Relationship

Atomistic analysis of the ion transport in polymer electrolytes for all-solid-state Li-ion batteries was performed using molecular dynamics simulations to investigate the relationship between Li-ion transport and polymer morphology. Polyethylene oxide (PEO) and poly(diethylene oxide-alt-oxymethylene), P(2EO-MO), were used as the electrolyte materials, and the effects of salt concentrations and polymer types on the ion transport properties were explored. The size and number of LiTFSI clusters were found to increase with increasing salt concentrations, leading to a decrease in ion diffusivity at high salt concentrations. The Li-ion transport mechanisms were further analyzed by calculating the inter/intra-hopping rate and distance at various ion concentrations in PEO and P(2EO-MO) polymers. While the balance between the rate and distance of inter-hopping was comparable for both PEO and P(2EO-MO), the intra-hopping rate and distance were found to be higher in PEO than in P(2EO-MO), leading to a higher diffusivity in PEO. The results of this study provide insights into the correlation between the nanoscopic structures of ion solvation and the dynamics of Li-ion transport in polymer electrolytes.

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