Vasopressin regulates apical and basolateral Na(+)-H+ antiporters in mouse medullary thick ascending limbs
| Autor: | D. Kikeri, Steven C. Hebert, A. Sun |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Vasopressin
medicine.medical_specialty Sodium-Hydrogen Exchangers Physiology Antiporter Intracellular pH Amiloride Mice Internal medicine medicine Renal medulla Animals Ion transporter Epithelial polarity Kidney Medulla Chemistry Cell Membrane Sodium Apical membrane Hydrogen-Ion Concentration Molecular biology Arginine Vasopressin medicine.anatomical_structure Endocrinology Loop of Henle Carrier Proteins hormones hormone substitutes and hormone antagonists medicine.drug Hydrogen |
| Zdroj: | The American journal of physiology. 262(2 Pt 2) |
| ISSN: | 0002-9513 |
| Popis: | We assessed in isolated perfused mouse medullary thick ascending limb (MTAL) segments Na(+)-H+ antiporter activity in both apical and basolateral membranes and the effects of arginine vasopressin (AVP) on the activities of these antiporters under isotonic conditions using 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein to monitor intracellular pH (pHi). When the apical Na(+)-H+ antiporter was inhibited in the absence of AVP with removal of luminal Na+ plus addition of 0.5 mM amiloride, a small but significant increase in pHi was observed after luminal NH4Cl-induced acidification of MTAL cells to pHi less than 6.7. This increase in pHi was dependent on basolateral Na+ and inhibited with 0.5 mM basolateral amiloride, consistent with the function of a basolateral Na(+)-H+ antiporter. Basolateral AVP (100 microU/ml) enhanced the rate of pHi recovery due to the basolateral Na(+)-H+ antiporter by more than twofold. In contrast, AVP decreased the apical Na(+)-H+ antiporter activity by 50%. In the absence of AVP, addition of 0.5 mM amiloride to the luminal perfusate reduced steady-state pHi by 0.40 +/- 0.07 units, whereas exposure of the basolateral membrane to the same concentration of amiloride had no effect on pHi (delta pHi = 0.01 +/- 0.01 units). AVP reduced the magnitude of cell acidification on exposure of apical membranes to amiloride (delta pHi = 0.16 +/- 0.03) but increased the pHi response to basolateral amiloride (delta pHi = 0.09 +/- 0.00). Thus Na(+)-H+ antiporters are present on both apical and basolateral membranes of the mouse MTAL in the absence of AVP. AVP stimulates the basolateral, while inhibiting the apical, Na(+)-H+ antiporter.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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