Dexamethasone-induced sodium influx in human lymphocytes.
We evaluated the direct effects of glucocorticoids on intracellular sodium content and cellular transport systems. Cytosolic free sodium concentration ([Na+]i) was measured in intact human lymphocytes using the sodium-sensitive fluorescent dye sodium-binding benzofuran-isophthalate. Administration of dexamethasone for 60 min increased lymphocytic [Na+]i from 17.6 +/- 2.0 mmol/L to 24.3 +/- 3.9 nmol/L (n = 12; P < 0.01). The dexamethasone-induced [Na+]i increase was abolished in the absence of extracellular sodium, by mifepristone and by actinomycin D. The dexamethasone-induced [Na+]i increase was also seen after inhibition of Na+,K(+)-ATPase by 1 mmol/L ouabain. The present results indicate that dexamethasone produces a trans-plasma membrane sodium influx probably by early occurring genomic effects.
Tepel
M
M
Medizinische Universitäts-Poliklinik, University of Münster, Germany.
Theilmeier
G
G
Teupe
C
C
Zander
J F
JF
Zidek
W
W
D001692:Biological Transport / Q000187:drug effects; D003609:Dactinomycin / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D008214:Lymphocytes / Q000187:drug effects* / Q000378:metabolism*; D015735:Mifepristone / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D012964:Sodium / Q000097:blood* / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors
D003609:Dactinomycin; D015735:Mifepristone; D010042:Ouabain; D003907:Dexamethasone; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase