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| ELECTRONEUTRAL K+/HCO3- COTRANSPORT IN CELLS OF MEDULLARY THICK ASCENDING LIMB OF RAT-KIDNEY |
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| Author(s): LEVIEL F, BORENSZTEIN P, HOUILLIER P, PAILLARD M, BICHARA M |
| Source: JOURNAL OF CLINICAL INVESTIGATION Volume: 90 Issue: 3 Pages: 869-878 Published: SEP 1992 |
| Times Cited: 38 References: 29 |
| Abstract: The renal medullary thick ascending limb (MTAL) of the rat absorbs bicarbonate through luminal H+ secretion and basolateral HCO3- transport into the peritubular space. To characterize HCO3- transport, intracellular pH (pHi) was monitored by use of the pH-sensitive fluorescent probe (2',7')-bis-(carboxyethyl)-(5,6)-carboxyfluorescein in fresh suspensions of rat MTAL tubules. When cells were preincubated in HCO3-/CO2-containing solutions and then abruptly diluted into HCO3-/CO2-free media, the pHi response was an initial alkalinization due to CO2 efflux, followed by an acidification (pHi recovery). The pHi recovery required intracellular HCO3-, was inhibited by 10(-4) M diisothiocyanostilbene-2-2'-disulphonic acid (DIDS), and was not dependent on Cl- or Na+. As assessed by use of the cell membrane potential-sensitive fluorescent probe 3,3'-dipropylthiadicarbocyanine, cell depolarization by abrupt Cl- removal from or addition of 2 mM barium into the external medium did not affect HCO3--dependent pHi recovery, and the latter was not associated per se with any change in potential difference, which indicated that HCO3- transport was electroneutral. The HCO3--dependent pHi recovery was inhibited by raising extracellular potassium concentration and by intracellular potassium depletion. Finally, as measured by use of a K+-selective extracellular electrode, a component of K+ efflux out of the cells was HCO3- dependent and DIDS sensitive. The results provide evidence for an electroneutral K+/HCO3-co-transport in rat MTAL cells. |
| Document Type: Article |
| Language: English |
Addresses:
1. HOP BROUSSAIS, DEPT PHYSIOL, 96 RUE DIDOT, F-75674 PARIS 14, FRANCE
2. UNIV PARIS 06, INSERM, U35, PHYSIOL & ENDOCRINOL CELLULAIRE RENALE LAB, F-75014 PARIS, FRANCE |
| Publisher: ROCKEFELLER UNIV PRESS, 1114 FIRST AVE, 4TH FL, NEW YORK, NY 10021 |
| Subject Category: Medicine, Research & Experimental |
| IDS Number: JN959 |
| ISSN: 0021-9738 |
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