Effect of dexamethasone on the lymphocytic Na+/H+antiporter activity
作者:
Martin Tepel,
Michael Pytlik,
Marcus van der Giet,
Hartmut Schlüter,
Joachim Jankowski,
Walter Zidek,
期刊:
Journal of Hypertension
(OVID Available online 1999)
卷期:
Volume 17,
issue 11
页码: 1553-1556
ISSN:0263-6352
年代: 1999
出版商: OVID
关键词: dexamethasone;sodium/proton antiporter;lymphocytes;fluorescent dye
数据来源: OVID
摘要:
ObjectiveThe effects of short-term administration of dexamethasone on sodium/proton antiporter (Na+/H+antiporter) in human lymphocytes were investigatedin vitro.MethodsCytosolic pHiin lymphocytes was measured spectrophotometrically using the pH-sensitive fluorescent dye 2′-7′-bis-carboxyethyl-5(6)-carboxyfluorescein at 530 nm with excitation wavelengths of 440 and 530 nm. The Na+/H+antiporter activity was determined after intracellular acidification using 100 mmol/l propionic acid.ResultsThe addition of 1 μmol/l dexamethasone significantly reduced cytosolic pHifrom 7.44 ± 0.03 to 7.25 ± 0.05 (mean ± SEM;P< 0.01). Incubation with dexamethasone for 40 min significantly reduced the Na+/H+antiporter activity from (9.19 ± 0.61) × 10−3pHi/s (n= 22) to (7.23 ± 0.49) × 10−3pHi/s (n= 22;P< 0.01). The effect of dexamethasone was time and concentration dependent. The apparent affinity of the Na+/H+antiporter was not significantly different in the absence or presence of dexamethasone. The inhibition of the Na+/H+antiporter by dexamethasone was abolished in the presence of the glucocorticoid receptor blocker, mifepristone.ConclusionDexamethasone directly inhibits the Na+/H+antiporter using a receptor-dependent pathway. This effect may be important for pharmacological side effects such as glucocorticoid-induced hypertension.
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