Effect of magnesium on cytosolic free sodium in human lymphocytes.
Cytosolic free sodium concentration ([Na+]i) was measured in intact human lymphocytes using the novel sodium-sensitive fluorescent dye sodium-binding benzofuran-isophthalate. In the presence of 1 mmol/l external Mg2+ the resting [Na+]i was significantly lower compared to the value in the absence of external Mg2+ (22.7 +/- 1.1 mmol/l vs. 37.6 +/- 1.4 mmol/l; p < 0.0001). The thapsigargin induced [Na+]i increase was significantly lower in the presence of 1 mmol/l external Mg2+ compared to the value in the absence of external Mg2+ (73.4 +/- 6.0 mmol/l vs. 120.7 +/- 5.8 mmol/l; p < 0.001). Since Mg2+ is known to be a cofactor of the membrane Na+,K(+)-ATPase these measurements in intact lymphocytes indicate that deprivation of external Mg2+ causes an increase of [Na+]i.
Tepel
M
M
Medizinische Universitäts-Poliklinik, University of Münster, Germany.
Schlotmann
R
R
Teupe
C
C
Zidek
W
W
D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008274:Magnesium / Q000494:pharmacology*; D012964:Sodium / Q000097:blood*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin
D013729:Terpenes; D019284:Thapsigargin; D012964:Sodium; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium