Evidence for a random entry of Ca2+ into human red cells

Under the influence of a Gardos channel activator, NS309, acting through an increase of the channels Ca2+ sensitivity, it is found that the single population behavior of a suspension of human red cells, showing normal distributed osmotic resistance and density, after addition of NS309 in a time dependent manner changes to a two population distribution, with an increasing fraction of cells having high osmotic resistance or high density.The increase with time of the high resistance fraction can be fitted to an exponential, with a time constant corresponding to about 50 min. Since the ‘remaining’ cell fraction is practically unchanged, this points to a sudden random activation of the individual cells, caused by Ca2+ entry through a channel like pathway.