Glucocorticoids enhance acid activation of the Na+/H+ exchanger 3 (NHE3)

Citation
Pm. Ambuhl et al., Glucocorticoids enhance acid activation of the Na+/H+ exchanger 3 (NHE3), J CLIN INV, 103(3), 1999, pp. 429-435
Citations number
21
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Medical Research General Topics
Journal title
JOURNAL OF CLINICAL INVESTIGATION
ISSN journal
0021-9738 → ACNP
Volume
103
Issue
3
Year of publication
1999
Pages
429 - 435
Database
ISI
SICI code
0021-9738(199902)103:3<429:GEAAOT>2.0.ZU;2-E
Abstract
In the absence of exogenous glucocorticoids, decreasing media pH (from 7.4 to 6.8) for 24 hours increased the Na+/H+ exchanger 3 (NHE3) activity in op ossum kidney (OKP) cells. 10(-7) M and 10(-8) M hydrocortisone increased NH E3 activity, and in their presence, acid incubation further increased NHE3 activity. Hydrocortisone (10(-9) M) had no effect on NHE3 activity, but in its presence, the effect of acid incubation on NHE3 activity increased twof old. Aldosterone (10(-8) M) had no effect. In the absence of hydrocortisone , acid incubation increased NHE3 protein abundance by 47%; in the presence of 10(-9) M hydrocortisone, acid incubation increased NHE3 protein abundanc e by 132%. The increase in NHE3 protein abundance was dependent on protein synthesis. However, 10(-9) M hydrocortisone did not modify the effect of ac id incubation to cause a twofold increase in NHE3 mRNA abundance. In the ab sence of protein synthesis, 10(-9) M hydrocortisone did potentiate an effec t of acid on NHE3 activity, which was due to trafficking of NHE3 to the api cal membrane. These results suggest that glucocorticoids and acid interact synergistically at the level of NHE3 translation and trafficking.