Na(+)-H+ antiporter and Na(+)-(HCO3-)n symporter regulate intracellular pH in mouse medullary thick limbs of Henle
| Autor: | A. Sun, D. Kikeri, Steven C. Hebert, S. Azar, Mark L. Zeidel |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Male
Sodium-Hydrogen Exchangers Physiology Intracellular pH Mice Inbred Strains Mice Oxygen Consumption Suspensions Extracellular medicine Renal medulla Cyclic AMP Animals Ion transporter Kidney Medulla Chemistry Sodium-Bicarbonate Symporters Intracellular Membranes Hydrogen-Ion Concentration Molecular biology Adenosine Amiloride Arginine Vasopressin Bicarbonates medicine.anatomical_structure Kidney Tubules Biochemistry Symporter Loop of Henle Protons Carrier Proteins Intracellular medicine.drug |
| Zdroj: | The American journal of physiology. 258(3 Pt 2) |
| ISSN: | 0002-9513 |
| Popis: | To determine mechanisms of intracellular pH (pHi) regulation in mouse medullary thick limbs (MTAL), pHi was measured in MTAL suspensions and in the isolated perfused MTAL by use of 2',7'-bis(carboxyethyl)-5(6)carboxyfluorescein (BCECF). A method to obtain MTAL suspensions from the mouse outer medulla is reported. Characterization of suspensions with microscopy, anti-Tamm-Horsfall antibody labeling, measurement of O2 consumption, and adenosine 3',5'-cyclic monophosphate responses to antidiuretic hormone indicated that these suspensions were highly purified for viable MTAL tubules. The resting pHi was 7.41 +/- 0.02 (means +/- SE) in N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid-buffered media and 7.23 +/- 0.02 in CO2- HCO3(-)-buffered media, both at extracellular pH 7.4. MTAL tubules exhibited rapid pHi recovery from intracellular acidification. Recovery of pHi was dependent on luminal Na+ (apparent Km = 13.2 +/- 3.2 mM) and was inhibited by amiloride (apparent Ki = 10.6 microM), consistent with the activity of an apical Na(+)-H+ antiporter. Antiporter activity was enhanced by acidification and was diminished at the resting pHi. Recovery from intracellular alkalinization (rapid withdrawal of CO2- HCO3-) was sensitive to the stilbene anion transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, Cl(-)-insensitive, and Na(+)-sensitive, consistent with the activity of a Na(+)-(HCO3-)n symporter. Both transporters were significantly involved in steady-state pHi regulation in the presence of CO2- HCO3-. In contrast, the Na(+)-H+ antiporter played the dominant role in steady-state pHi regulation in the absence of CO2- HCO3-. |
| Databáze: | OpenAIRE |
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