Calcium transport in the thick ascending limb of Henle. Heterogeneity of function in the medullary and cortical segments.

Suki, Wadi N.; Rouse, D.; Ng, Roland C.K.; Kokko, Juha P.

doi:10.1172/jci109928

Cited by 120 publications

(45 citation statements)

References 22 publications

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“…In previous studies, the above maneuvers were sufficient to prevent binding of isotopic calcium from static solutions in the pipettes for at least 2 h. Furthermore, recovery of isotopic calcium in the bath closely matches that which disappears from the perfusate (10,11).…”

Section: Methodsmentioning

confidence: 58%

“…Bourdeau and Burg (14) and Shareghi and Agus (26) have well demonstrated the voltage-dependence of presumably passive, net calcium transport in the rabbit cortical thick ascending limb of Henle, yet parathyroid hormone (PTH) is able to enhance net calcium absorption without a change in PD (26,27). Similarly, Suki et al (10) have also demonstrated apparently passive, voltage-dependent calcium transport in the medullary thick ascending limb, which is enhanced by calcitonin in the absence of any change in PD (1 1). One explanation for such findings is the presence of an active transport mechanism of low basal activity, which is enhanced or uncovered in the presence of a hormone such as PTH or calcitonin (11).…”

Section: Discussionmentioning

confidence: 97%

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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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Section: Methodsmentioning

confidence: 58%

Section: Discussionmentioning

confidence: 97%

Calcium transport in the rabbit superficial proximal convoluted tubule.

Ng¹,

Rouse²,

Suki³

1984

J. Clin. Invest.

Self Cite

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“…It was reported (Suki et al 1980) that the mTAL possesses passive potential-dependent net Ca 2+ reabsorption. However, it was also reported (Mandon et al 1993) that the mTAL of rat kidney can reabsorb neither Mg 2+ nor Ca 2+ , whatever transepithelial voltage (Vte).…”

Section: Contribution Of the Casr To Transepithelial Ca 2+ Transport mentioning

confidence: 99%

Chloride-Dependent Intracellular pH Regulation via Extracellular Calcium-Sensing Receptor in the Medullary Thick Ascending Limb of the Mouse Kidney

Aslanova

Morimoto

Farajov

et al. 2006

Tohoku J. Exp. Med.

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The extracellular calcium-sensing receptor (CaSR) located in either luminal or basolateral cell membranes of various types of renal tubules including proximal tubules, Henle's loop and collecting ducts has been thought to play a fundamental role in electrolyte metabolism. To further identify the physiological roles of the CaSR, we examined the effects of Ca 2+ and calcimimetics neomycin (Neo), gentamicin and gadolinium chloride (Gd 3+ ) on the intracellular pH (pHi) of in vitro microperfused mouse medullary thick ascending limb (mTAL) cells of Henle's loop, by loading the cells with fluorescent pH indicator 2′,7′-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein and measuring the ratio of fluorescence emission at 530 nm after exciting the dye at 490 and 440 nm. In a steady-state condition in Hepes-buffered solution, the pHi in the mTALs was 7.29 ± 0.04 (n = 9). A concentration of 200 μ mol/l Neo in the basolateral side decreased the pHi after 1 min by −0.13 ± 0.02 (n = 34, p < 0.0001). The other calcimimetics showed similar effects on pHi, whereas none of these calcimimetics in the lumen affected pHi. Na + removal or the inhibition of Na + and proton transport with amiloride, bumetanide, or bafilomycin did not eliminate the effect of Neo on pHi. On the other hand, Cl − removal clearly eliminated the Neo-induced pHi decrease (−0.06 ± 0.01 vs −0.00 ± 0.05 in Cl − removal, n = 4, p < 0.003). Thus, we have demonstrated for the first time that the CaSR is involved in the regulation of the pHi in the mTAL and requires Cl − to exert its effect. intracellular pH; renal medulla; chloride; amiloride; BCECF

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“…The major sites at which PTH stimulates renal calcium absorption are cortical thick ascending limbs of Henle's loop (1)(2)(3)(4), distal convoluted tubules (5,6) or, in the rabbit, in connecting tubules (7)(8)(9). In these hormone-sensitive nephron segments, PTH increases active, transcellular calcium trans-port (3, [10][11][12].…”

Section: Introductionmentioning

confidence: 99%