Active transport potentials, membrane diffusion potentials and streaming potentials across rat kidney proximal tubule

Frömter, Eberhard; Gessner, K.

doi:10.1007/bf00603513

Cited by 85 publications

(21 citation statements)

References 20 publications

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“…In earlier studies we have demonstrated that changes in peritubular capillary perfusate composition did not affect luminal fluid composition (4). In the present set of studies, we utilized rapid retrograde perfusion, as described by Fromter and Gessner (21), to control the luminal fluid composition. This technique has the advantage of allowing rapid luminal fluid changes with the least number of tubular punctures.…”

Section: Discussionmentioning

confidence: 93%

Cell pH in the rat proximal convoluted tubule. Regulation by luminal and peritubular pH and sodium concentration.

Alpern¹,

Chambers²

1986

J. Clin. Invest.

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To examine the relative roles of apical and basolateral membrane transport mechanisms in the regulation of cell pH in the proximal convoluted tubule, cell pH was measured in the in vivo microperfused rat tubule using fluorescence. Decreasing luminal pH by 0.7 pH units caused cell pH to decrease by 0.08 pH units, whereas a similar decrease in peritubular pH caused cell pH to decrease by 0.32 pH units. Inhibition of basolateral membrane bicarbonate transport with peritubular 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonate (SITS) enhanced the response to luminal fluid acidification. Removal of luminal sodium caused a small transient acidification which was followed by a late alkalinization. Peritubular SITS increased the magnitude of the transient acidification, and eliminated the late alkalinization. The acidification was partially inhibited by luminal amiloride. The results demonstrate sodium-coupled processes on both the apical (Na/H antiport) and basolateral (Na/HCO3 symport) membranes. Basolateral membrane transporters are more important determinants of cell pH.

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Section: Discussionmentioning

confidence: 93%

Cell pH in the rat proximal convoluted tubule. Regulation by luminal and peritubular pH and sodium concentration.

Alpern¹,

Chambers²

1986

J. Clin. Invest.

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“…Fromter & Gessner, 1974) in terms of glucose-stimulated enhancement of electrogenic cotransport of sodium. However, we emphasize that such electrical data provide no evidence as to the quantitative significance of glucose-sodium cotransport relative to total proximal tubular reabsorption of sodium and fluid; and in another study, the electrical potential difference was found not to be directly related to water reabsorption (Cardinal et al 1975).…”

Section: Discussionmentioning

confidence: 99%

Effects of glucose on water and sodium reabsorption in the proximal convoluted tubule of rat kidney.

Bishop¹,

Green²,

Thomas³

1978

The Journal of Physiology

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SUMMARY1. The effects of glucose on sodium and water reabsorption by rat renal proximal tubules was investigated by in situ microperfusion of segments of proximal tubules with solutions containing glucose or no glucose, with and without phlorizin.2. Absence of glucose did not significantly alter net water flux. Sodium flux was reduced by about 10 % but this was not statistically significant.3. In the absence of glucose in the perfusion fluid net secretion of glucose occurred. 4. Phlorizin reduced either net reabsorption or net secretion of glucose; and net water flux.5. The data suggest that in later parts of the proximal convoluted tubule some sodium may be co-transported with glucose, but that this represents only a small fraction of the total sodium reabsorption.6. It is suggested that the glucose carrier is reversible and in appropriate circumstances could cause glucose secretion.7. Althoughphlorizin alters net water flux the underlying mechanisms are not clear. 8. The calculated osmolality of the reabsorbate was significantly greater than the perfusate osmolality and greater than plasma osmolality although this was not quite significant statistically.

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“…After 5-7 min, this pipette was removed and a second luminal pipette was placed in a more distal loop of the same nephron. This second pipette, which was similar to that used in the peritubular capillary except that it had a smaller tip (7)(8)(9) Mum), perfused the proximal tubular lumen in a retrograde fashion as previously de-scribed (36,37). This method of lumen and capillary perfusion has been demonstrated to give complete control of luminal and capillary fluids (25,36).…”

Section: Methodsmentioning

confidence: 99%

Role of the Na+/H+ antiporter in rat proximal tubule bicarbonate absorption.

Preisig¹,

Ives²,

Cragoe³

et al. 1987

J. Clin. Invest.

161

103

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Amiloride and the more potent amiloride analog, 54N-t-butyl) amiloride (t-butylamiloride), were used to examine the role of the Na+/H+ antiporter in bicarbonate absorption in the in vivo microperfused rat proximal convoluted tubule. Bicarbonate absorption was inhibited 29, 46, and 47% by 0.9 mM or 4.3 mM amiloride, or 1 mM t-butylamiloride, respectively. Sensitivity of the Na+/H+ antiporter to these compounds in vivo was examined using fluorescent measurements of intracellular pH with (2',7')-bis(carboxyethyl)-(5,6)-carboxyfluorescein (BCECF). Amiloride and t-butylamiloride were shown to be as potent against the antiporter in vivo as in brush border membrane vesicles. A model of proximal tubule bicarbonate absorption was used to correct for changes in the luminal profiles for pH and inhibitor concentration, and for changes in luminal flow rate in the various series. We conclude that the majority of apical membrane proton secretion involved in transepithelial bicarbonate absorption is mediated by the Na+-dependent, amiloride-sensitive Na+/H+ antiporter. However, a second mechanism of proton secretion contributes significantly to bicarbonate absorption. This mechanism is Na+-independent and amiloride-insensitive.

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Active transport potentials, membrane diffusion potentials and streaming potentials across rat kidney proximal tubule

Cited by 85 publications

References 20 publications

Cell pH in the rat proximal convoluted tubule. Regulation by luminal and peritubular pH and sodium concentration.

Cell pH in the rat proximal convoluted tubule. Regulation by luminal and peritubular pH and sodium concentration.

Effects of glucose on water and sodium reabsorption in the proximal convoluted tubule of rat kidney.

Role of the Na+/H+ antiporter in rat proximal tubule bicarbonate absorption.

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