Mg2+ influx into Mg(2+)-depleted reticulocytes.

Mg(2+)-depleted rat reticulocytes reincubated in Mg(2+)-containing media expressed net Mg2+ influx, which was the same in NaCl, choline Cl and sucrose medium. Km of Mg2+ influx amounted to 1.2 mM and Vmax to 0.9 mmol/l cells x h. Mg2+ influx into reticulocytes was inhibited by amiloride, quinidine and imipramine. Mg2+ uptake together with Cl- for charge compensation could be excluded. However, the cation which must be exchanged for Mg2+ in Mg2+ uptake could not be identified because of the low rate of Mg2+ influx.