Dear Confocalists, We have problems measuring Ca2+ in Red Blood Cells. There is not only a bad loading with fura-2 or Indo-1 but also a very high background fluorescence. Fluo-3 is working better but it is harder to quantify. Has anyone a suggestion to measure Ca2+ in intact cells. Thanks [log in to unmask] Laboratory of Physiology Gasthuisberg O/N Herestraat 49 B3000 Leuven ph: +32-16-34 57 27 fax: +32-16-34 59 91