scholarly journals ACTION OF TRITON X-100 ON CHLOROPLAST MEMBRANES

1967 ◽  
Vol 33 (2) ◽  
pp. 395-410 ◽  
Author(s):  
David W. Deamer ◽  
Antony Crofts
Keyword(s):  
Ion Transport ◽  
Conformational Changes ◽  
Active Material ◽  
Active Species ◽  
Hydrogen Ion ◽  
Electron Microscopic ◽  
Chloroplast Membranes ◽  
Ionic Equilibrium ◽  
Hydrogen Ion Transport ◽  
Triton X

Addition of Triton X-100 to chloroplast suspensions to a final concentration of 100–200 µM causes an approximate tripling of chloroplast volume and complete inhibition of light-induced conformational changes, light-dependent hydrogen ion transport, and photophosphorylation. Electron microscopic studies show that chloroplasts treated in this manner manifest extensive swelling in the form of vesicles within their inner membrane structure. Triton was adsorbed to chloroplast membranes in a manner suggesting a partition between the membrane phase and the suspending medium, rather than a strong, irreversible binding. This adsorption results in the production of pores through which ions may freely pass, and it is suggested that the inhibition of conformational changes, hydrogen ion transport, and photophosphorylation by Triton is due to an inability of treated chloroplast membranes to maintain a light-dependent pH gradient. The observed swelling is due to water influx in response to a fixed, osmotically active species within the chloroplasts, after ionic equilibrium has occurred. This is supported by the fact that chloroplasts will shrink upon Triton addition if a nonpenetrating, osmotically active material such as dextran or polyvinylpyrrolidone is present externally in sufficient concentration (>0.1 mM) to offset the osmotic activity of the internal species.

Electro-osmosis and hydrogen-ion transport in cation-exchange membranes

1967 ◽  
Vol 20 (12) ◽  
pp. 2575 ◽  
Author(s):  
R Arnold ◽  
DA Swift
Keyword(s):  
Ion Transport ◽  
Cation Exchange ◽  
Acid Concentration ◽  
Water Flux ◽  
Transference Number ◽  
Hydrogen Ion ◽  
Transference Numbers ◽  
Transport Numbers ◽  
Electro Osmosis ◽  
Hydrogen Ion Transport

Hydrogen-ion transport numbers, water transference numbers, and acid absorption are reported for some cation-exchange membranes in presence of 0.1N, 1.0N, and 5.0N sulphuric acid. The transport numbers of hydrogen ion remain fairly close to unity even at the highest acid concentration; this is largely due to the retardation of the anions by the electro-osmotic water flux. With increasing acid concentration the water transference number falls to a lower limit of 1.0 mole per faraday; with the driest membrane used this value is obtained at all acid concentrations used. This behaviour suggests that when there are less than about 11 moles of water available per hydrogen ion in the membrane, association occurs between sulphonate groups and hydrogen ions, with consequent immobilization of the latter.

Hydrogen ion transport in Epithelia

FEBS Letters ◽  
1982 ◽  
Vol 140 (1) ◽  
pp. 145-146
Author(s):  
R.J. Naftalin
Keyword(s):  
Ion Transport ◽  
Hydrogen Ion ◽  
Hydrogen Ion Transport

Hydrogen ion secretion by the rat distal nephron: adaptation to chronic alkali and acid ingestion

1983 ◽  
Vol 245 (3) ◽  
pp. F349-F358
Author(s):  
C. Kornandakieti ◽  
R. Grekin ◽  
R. L. Tannen
Keyword(s):  
Ion Transport ◽  
Rat Kidney ◽  
Hydrogen Ion ◽  
Distal Nephron ◽  
Urine Ph ◽  
Ion Secretion ◽  
Titratable Acid ◽  
Chronic Ingestion ◽  
Hydrogen Ion Transport ◽  
Secretory Capacity

Isolated rat kidneys perfused at a low bicarbonate concentration were subjected to increased rates of buffer excretion, provided as creatinine, in order to examine the maximal hydrogen ion secretory capacity of the distal nephron. Preliminary experiments with kidneys from normal rats indicated that the quantity of hydrogen ion that titrated creatinine from urine pH to a pH of 6.0, designated TA-pH 6.0, provided an index of net hydrogen ion secretion by a functional segment of the distal nephron. With this technique the response of distal nephron hydrogen ion transport to ingestion of both acid and alkali loads was examined. Perfused kidneys from rats with chronic metabolic acidosis, produced by drinking 1.5% NH4Cl for 3-5 days, excreted urine with a lower pH and higher total titratable acid and TA-pH 6.0 than appropriate controls. Perfused kidneys from rats that ingested NaHCO3 for 7 days exhibited a higher urine pH and lower rates of total titratable acid and TA-pH 6.0 than controls. By contrast, kidneys from rats acutely tube-fed NaHCO3 3 h prior to study showed no change in urinary acidification parameters. Thus, chronic ingestion of an acid load stimulates, and chronic ingestion of an alkali load inhibits, the intrinsic hydrogen ion secretory capacity of the rat kidney at a distal nephron site. This intrinsic adaptation of the hydrogen ion transport mechanism is not secondary to changes in aldosterone because rats that ingested NaHCO3 chronically had higher plasma aldosterone levels than controls.

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