Free-flow potential profile along rat kidney proximal tubule

Frömter, Eberhard; Gessner, K.

doi:10.1007/bf00603512

Cited by 88 publications

(24 citation statements)

References 16 publications

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“…In contrast, the Na permselective juxtamedullary segments displayed lumen-negative potentials ranging from 0 to -2.0 mV (one segment had a PD of +0.6 mV) with a mean±SEM of -0.6±0.2 mV. These electrical findings are consistent with previous in vivo and in vitro studies oflater SFPCT perfused with either naturally occurring later proximal tubule fluid or solutions simulating later proximal tubule fluid (13,(23)(24)(25) and with a previous in vitro study of JMPCT (7). Of interest is the finding that in spite of the differing electrical charge orientation of the lumen PD, fluid reabsorption was similar in SFPCT and JMPCT.…”

Section: Resultssupporting

confidence: 89%

Characteristics of Volume Reabsorption in Rabbit Superficial and Juxtamedullary Proximal Convoluted Tubules

Jacobson¹

1979

J. Clin. Invest.

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A B S T R A C T Segments of superficial and juxtamedullary proximal convoluted tubules of the rabbit were perfused in vitro to examine the mechanisms responsible for net volume reabsorption. The very early postglomerular segments were not studied. Fluid reabsorptive rates and transepithelial potential differences were compared under various conditions: (a) with perfusate that simulated glomerular filtrate; (b) with perfusate that lacked glucose, amino acids, and acetate and that had HCO3 and Cl concentrations of 5 and 140 mM, respectively; (c) with perfusate that lacked glucose, amino acids, and acetate but with 20 meq ofNaHCO3 replaced with 20 meq ofNa cyclamate; (d) with the same perfusate as in b but in the presence of ouabain in the bath; (e) with ultrafiltrate of rabbit serum titrated with HC1 to final HCO3 and Cl concentrations of 2 and 134 mM, respectively. Tubules were perfused with this titrated ultrafiltrate at 37°C, 21°C, and in the presence of 0.1 mM ouabain in the bath. Bath fluid in all experiments was regular rabbit serum. Under conditions a and b superficial proximal convoluted tubule (SFPCT) and juxtamedullary proximal convoluted tubule (JMPCT) behaved similarly with the exception that SFPCT exhibited a lumen-positive and JMPCT a lumen-negative electrical potential under condition b. However, undeT condition c SFPCT failed to exhibit net volume reabsorption, whereas reabsorption in JMPCT continued unchanged. Ouabain did not affect volume reabsorption in SFPCT under condition

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Section: Resultssupporting

confidence: 89%

Characteristics of Volume Reabsorption in Rabbit Superficial and Juxtamedullary Proximal Convoluted Tubules

Jacobson¹

1979

J. Clin. Invest.

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“…Measurement of the transtubular potential profile along the proximal tubule (Fromter et al 1973;Barratt et al 1974;Fromter & Gessner, 1974;Seely & Chirito, 1975) suggests that the reabsorptive characteristics of the early part of the proximal tubule differ from those found in later segments. Of particular relevance to the present work is the finding that in the early part of the proximal tubule there is only negligible reabsorption of chloride (Le Grimellec, 1975).…”

Section: Caculionsmentioning

confidence: 99%

Comparison of chloride concentration and osmolality in proximal tubular fluid, peritubular capillary plasma and systemic plasma in the rat.

Atherton¹

1977

The Journal of Physiology

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SUMMARY1. Chloride concentration and osmolalities were compared in consecutively collected samples of proximal tubular fluid, peritubular capillary plasma and systemic plasma.2. Mean chloride concentrations (m-mole/l) were 141'3 + 2-6 in tubular fluid, 114-8 + 1*7 in peritubular capillary plasma and 119-4 + 1-8 in systemic plasma. 4. These differences are discussed in relation to the anatomical and functional organization of the peritubular capillaries and renal tubules.

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“…The first is that in free-flow micropuncture experiments in the presence of an osmotic diuresis, the [TF/UF]ca concentration ratio falls to < 1.0, which suggests transport of calcium against a concentration gradient (1, 2). A mitigating factor, however, is that a lumen-positive potential difference (PD) exists beyond the very early proximal convolutions (5), which could provide a driving force for calcium transport. A second line of evidence is that Ulirich et al (6), in an in situ tubule microperfusion study with simultaneous capillary perfusion, found that more calcium was transported than could be accounted for by the calculated electrochemical gradient.…”

Section: Introductionmentioning

confidence: 99%

Calcium transport in the rabbit superficial proximal convoluted tubule.

Ng¹,

Rouse²,

Suki³

1984

J. Clin. Invest.

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Abstract. Calcium transport was studied in isolated S2 segments of rabbit superficial proximal convoluted tubules. '"Ca was added to the perfusate for measurement of lumen-to-bath flux (JibCa), to the bath for bath-to-lumen flux (JbIc), and to both perfusate and bath for net flux (Jnetc). In these studies, the perfusate consisted of an equilibrium solution that was designed to minimize water flux or electrochemical potential differences (PD). Under these conditions, JibCa (9.1 ± 1.0 peq/mm min) was not different from JblCa (7.3±1.3 peq/mm min), and Jntc1 was not different from zero, which suggests that calcium transport in the superficial proximal convoluted tubule is due primarily to passive transport. The efflux coefficient was 9.5±1.2 X 10-5 cm/ s, which was not significantly different from the influx coefficient, 7.0±1.3 X 10-5 cm/s. When the PD was made positive or negative with use of different perfusates, net calcium absorption or secretion was demonstrated, respectively, which supports a major role for passive transport. These results indicate that in the superficial proximal convoluted tubule ofthe rabbit, passive driving forces are the major determinants of calcium transport.

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Free-flow potential profile along rat kidney proximal tubule

Cited by 88 publications

References 16 publications

Characteristics of Volume Reabsorption in Rabbit Superficial and Juxtamedullary Proximal Convoluted Tubules

Characteristics of Volume Reabsorption in Rabbit Superficial and Juxtamedullary Proximal Convoluted Tubules

Comparison of chloride concentration and osmolality in proximal tubular fluid, peritubular capillary plasma and systemic plasma in the rat.

Calcium transport in the rabbit superficial proximal convoluted tubule.

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