TY - JOUR AU - Fijnheer, Rob; Homburg, Christa H E; Hooibrink, Berend; Boomgaard, Martine N; de Korte, Dirk; Roos, Dirk TI - Loss of Thrombin-Induced Ca2+ Mobilization in a Subpopulation of Platelets during Storage SN - 0340-6245 SN - 2567-689X PY - 1991 JO - Thromb Haemost JF - Thrombosis and Haemostasis LA - EN VL - 66 IS - 09 SP - 350 EP - 354 DA - 2018/07/25 AB - Thrombin-induced changes in cytosolic free Ca2+ ([Ca2+]i) were studied in human platelets that had been stored for up to 6 days. Changes in [Ca2+]i were measured with Indo-1-loaded platelets and quantitated with two different methods: (i) measurement of the changes in total fluorescence; (ii) measurement of the [Ca2+]i changes in individual platelets in a flow cytometer, allowing the detection of non-responding platelets. The maximal concentration of [Ca2+]i after stimulation with 0.5 U of thrombin/ml decreased from 544 ± 58 nM (mean ± SEM, n = 6) on day 0, to 276 ± 9 nM on day 3 and to 203 ± 23 nM on day 6. The percentage of platelets responding to 0.5 U of thrombin/ml declined from 90 ± 2% on day 0 to 72 ± 4% on day 3, and to 47 ± 8% on day 6. Nevertheless, also the responding platelets showed a decreased rise in [Ca2+]i.The study shows that during platelet storage a decrease in the rise in [Ca2+]i upon thrombin stimulation occurs. This decrease is partly due to the formation of a subpopulation of platelets that is completely unresponsive and partly due to a decreased responsiveness in the remainder of the platelets; it is not due to a gradual decline in [Ca2+]i rise in all platelets. This phenomenon provides new insight in the functional defect of stored platelets. PB - Schattauer GmbH DO - 10.1055/s-0038-1646419 UR - http://www.thieme-connect.com/products/ejournals/abstract/10.1055/s-0038-1646419 ER -