IONIC CALCIUM CONTENT OF LIGHT DENSE HUMAN RED-CELLS SEPARATED BY PERCOLL DENSITY GRADIENTS

In this paper we have compared the adequacy of two methods using Perco ll density gradients to separate light and dense erythrocytes from fre sh human blood. After measuring the distribution of some classical age -markers such as haemoglobin, potassium and creatine contents, it was found that preformed gradients generated more stringent conditions for age-related density separations. Employing such gradients, the free C a2+ content of above sub-populations was assessed with Fura-2, under c onditions where the viscosity effect was abolished. In five experiment s, the free Ca2+ content(mean value +/- 1 S.D.) was 8.4 +/- 2.82 nM an d 31.2 +/- 13.0 nM for the 7-10% lightest and densest cells, respectiv ely. These results are discussed in connection to red cell senescence.