Altered Calcium and Sodium Metabolism in Red Blood Cells of Hypertensive Man: Assessment by Ion-selective Electrodes

Altered calcium metabolism in red blood cells of hypertensives: Persistent marker or sequel of essential hypertension?

“…Blaustein [1] postulated an Na/Ca exchange mechanism, thus linking elevated intracellular Na and Ca levels which were found concordantly elevated in RBCs of hypertensives [13]. In a previous paper [12], we reported an abnormality of RBC Ca metabolism in hypertensives under metabolic depletion. While not representing a secondary effect of elevated blood pressure alterations of membrane systems, these alterations should persist after blood pressure normalization by antihypertensive therapy.…”

“…As described previously [12], washed RBCs were placed in a medium containing 130 mM NaC1, 15 mM Tris/HC1 (pH 7.4), 2.5 mM CaCI2, 4 mM KC1, and 30 mM desoxy-D-glucose (Fluka, Buchs, Switzerland, No 31060) at 37 ° C for metabolic depletion. At time 0, 24, and 48 h, aliquots of 0.5 ml…”

“…At time 0, 24, and 48 h, aliquots of 0.5 ml RBCs were removed and washed three times with 10ml ice-cold isotonic MgC12 solution (23g MgC122H20/1) and frozen at -18 ° C. For determination of free intracellular electrolytes ion-selective electrodes (tip diameter 5 ram) containing neutral carriers [10] were placed in RBCs hemolized after being freeze-thawed (for details see [12]). …”

“…In this regard, interest was mainly focused on sodium (Na) and calcium (Ca), the latter being considered an intracellular messenger for the contractile force. Previously, we demonstrated that in metabolically depleted RBCs of essential hypertensives intracellular calcium increased at a faster rate than in RBCs of normotensives [12]. In the present paper the effects of antihypertensive therapy in vivo and simulation of increased mechanical stress by cell homogenization in vitro were studied with regard to the Ca influx into RBCs.…”