The Ca-45(2+) influx into right-side-out resealed ghosts (RG) prepared from human red blood cells (RBC) was measured. The Ca-45(2+) equilibration occurred with t(1/2) = 2.5 min and the steady-state was reached after 17 min with the level of 22 +/- 2 mumol/L-packed (cells) at 37degreesC. The rate of the influx was 97 +/- 17 mumol/L-packed (cells) h. The Ca-45(2+) influx was saturated with [Ca2+](0) at 4 mmol/L and was optimal at pH 6.5 and 30 degreesC. Divalent cations (10(-4)-10(-6) mol/L), nifedipine (10(-5)-10(-4) mol/L), DIDS (up to 10(-4) mol/L), and quinidine (10(-4)-10(-3) mol/L), inhibited the Ca-45(2+) influx while uncoupler (10(-6)-10(-5) mol/L) stimulated it. In contrast to intact RBC, vanadate inhibited the Ca-45(2+) influx when added to the external medium, however, the stimulation was observed when vanadate was present in media during both lysis and resealing. PMA had no effect under conditions found to stimulate the Ca2+ influx in intact RBC. The results show that the Ca2+ influx into RG is a carrier-mediated process but without control by protein kinase C and that the influx and efflux of Ca2+ are coupled via the H+ homeostasis similarly as in intact RBC but with modified mechanism. (C) 2004 Elsevier Inc. All rights reserved.