Reinvestigation of the transepithelial P. D. in the proximal tubule of necturus kidney

Planelles, Gabrielle; Moreau, Karen; Anagnostopoulos, T.

doi:10.1007/bf00584696

Cited by 3 publications

(1 citation statement)

References 30 publications

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“…A V TE close to zero was recorded in early experiments by Anagnostopoulos in the amphibian PT [7,9]. The same group further determined V TE along the length of the amphibian PT [33,80]. In the early portion of Necturus PT in vivo V TE is −1 mV, and is positive (+0.6 mV) in the late portion.…”

Section: Introductionmentioning

confidence: 98%

Chloride transport in the renal proximal tubule

Planelles

2004

Pflugers Arch - Eur J Physiol

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The renal proximal tubule is responsible for most of the renal sodium, chloride, and bicarbonate reabsorption. Micropuncture studies and electrophysiological techniques have furnished the bulk of our knowledge about the physiology of this tubular segment. As a consequence of the leakiness of this epithelium, paracellular ionic transport--in particular that of Cl(-)--is of considerable importance in this first part of the nephron. It was long accepted that proximal Cl(-) reabsorption proceeds solely paracellularly, but it is now known that transcellular Cl(-) transport also exists. Cl(-) channels and Cl(-)-coupled transporters are involved in transcellular Cl(-) transport. In the apical membrane, Cl(-)/anion (formate, oxalate and bicarbonate) exchangers represent the first step in transcellular Cl(-) reabsorption. A basolateral Cl(-)/HCO(3)(-) exchanger, involved in HCO(3)(-) reclamation, participates in the rise of intracellular Cl(-) activity above its equilibrium value, and thus also contributes to the creation of an outwardly directed electrochemical Cl(-) gradient across the cell membranes. This driving force favours Cl(-) diffusion from the cell to the lumen and to the interstitium. In the basolateral membrane, the main mechanism for transcellular Cl(-) reabsorption is a Cl(-) conductance, but a Na(+)-driven Cl(-)/HCO(3)(-) exchanger may also participate in Cl(-) reabsorption.

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Section: Introductionmentioning

confidence: 98%

Chloride transport in the renal proximal tubule

Planelles

2004

Pflugers Arch - Eur J Physiol

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In Vivo Study of Transepithelial Potential Difference (TEPD) in Proximal Convoluted Tubules of Rat Kidney by Synchronization Modulation Electric Field

2014

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Synchronization modulation (SM) electric field has been shown to effectively activate function of Na(+)/K(+) pumps in various cells and tissues, including skeletal muscle cells, cardiomyocyte, monolayer of cultured cell line, and peripheral blood vessels. We are now reporting the in vivo studies in application of the SM electric field to kidney of living rats. The field-induced changes in the transepithelial potential difference (TEPD) or the lumen potential from the proximal convoluted tubules were monitored. The results showed that a short time (20 s) application of the SM electric field can significantly increase the magnitude of TEPD from 1-2 mV to about 20 mV. The TEPD is an active potential representing the transport current of the Na/K pumps in epithelial wall of renal tubules. This study showed that SM electric field can increase TEPD by activation of the pump molecules. Considering renal tubules, many active transporters are driven by the Na(+) concentration gradient built by the Na(+)/K(+) pumps, activation of the pump functions and increase in the magnitude of TEPD imply that the SM electric field may improve reabsorption functions of the renal tubules.

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Cell and luminal activities of chloride, potassium, sodium and protons in the late distal tubule of Necturus kidney.

Anagnostopoulos

Planelles

1987

The Journal of Physiology

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SUMMARY1. Double-barrelled (selective vs. conventional) microelectrodes were used to assess the steady-state activities (a) of the ions Cl-, K+, Na+ and H' in peritubular blood capillaries (abld) and in cell (ace11) and lumen (alum) of the late distal tubule2. acl1, acm and abl were 5-5 + 0-3, 11P8 + 1I0 and 70 5 + 0-1 mm, respectively. They were used to compute the chemical potentials for Cl-across the three diffusive barriers of the tissue. Basolateral and apical membrane potentials were -74-3 + 1 1 and -60-1+2-0 mV, respectively (cell negative); the lumen was thus negative with respect to blood, by 13-6 + 1-5 mV. The electrochemical potential difference (e.p.d.) for Cl-of 42 mV across the apical membrane opposes Cl-absorption, implying active apical Cl-uptake, since Cl-is known to be absorbed in the l.d.t. Basolateral Cl-exit is favoured by an e.p.d. of 10 mV.3. aKe1 a Km and abl were 65-8 + 0-8, 2-5 + 0-1 and 2-5 + 0-1 mm, respectively. The electrochemical distribution of K+ indicates that K+ absorption, if present, proceeds against an adverse apical e.p.d. of 18 mV. Basolateral K+ distribution is close to its electrochemical equilibrium, suggesting high K+ permeability at this membrane.4. aea was 9 0 +0-4 mm, abd 71-0+0-3 mm, and a Na was approximated at about 9 mm. Diffusive Na+ entry from lumen to cell is favoured by an e.p.d. close to 65 mV. Basolateral Na+ exit must be active, since it proceeds against an e.p.d. of 130 mV.5. Cell, luminal and blood pH were 7-14 + 0 03, 6-52 + 0-08 and 7-37 + 0 04, respectively. The luminal electrochemical potential of H+ is higher than that of cell (by 91 mV) and blood (by 34 mV) indicating that proton secretion into the lumen must be active.6. The e.p.d. of each ion across the epithelium opposes, by its orientation, the established direction of net transepithelial ion transport, suggesting that the shunt pathway may serve only for back-diffusion.* The authors' names are in alphabetical order.

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Reinvestigation of the transepithelial P. D. in the proximal tubule of necturus kidney

Cited by 3 publications

References 30 publications

Chloride transport in the renal proximal tubule

Chloride transport in the renal proximal tubule

In Vivo Study of Transepithelial Potential Difference (TEPD) in Proximal Convoluted Tubules of Rat Kidney by Synchronization Modulation Electric Field

Cell and luminal activities of chloride, potassium, sodium and protons in the late distal tubule of Necturus kidney.

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