A complete platelet system for metabolic studies: Pure, defined, and viable over 8 hours

We have been using a human platelet preparation to investigate various aspects of cellular metabolism. These experiments require a pure, quantitated platelet preparation that is viable for up to 8 h. The purity of the preparation has previously been characterized and we have now assessed its viability over 8 h and developed a simple spectrophotometric counting method. This method of counting results in estimations that are within 6% of those from an electronic cell counter (Coulter). Pure platelets stored in a Hepes physiological saline were resuspended periodically in autologous plasma to assess function over 24 h. The platelets consumed oxygen, changed shape, aggregated, and released dense granule ATP at all times. There was a slow and linear decrease in the various processes with time, ranging from 1.7% per hour for oxygen consumption to 3.8% per hour for percentage aggregation. The preparation is therefore not stable, but the changes with time are small and defined and it represents a useful system for the study of platelet and cell biology.