Biochemical Changes of RBCs as a consequence of Increased Rigidity: K+ and free Hb for RBCs store in CPDA-1, AS-1, and SOLX (N = 6). Data was fit via linear regression and slopes, which are indicative of rate of deterioration, are presented. (A). Concentration of K+ in blood released from RBCs tracked over 35 days for RBCs stored in CPDA-1, AS-1, and SOLX. Slopes from linear regression were determined to be: CPDA-1 (m = 1.4), AS-1 (m = 1.1), and SOLX (m = 0.90) (B). Concentration of free hemoglobin not bound to RBCs tracked over 35 days for RBCs stored in AS-1, CPDA-1, and SOLX. Slopes from linear regression were determined to be: CPDA-1 (m = 1.34), AS-1 (m= 1.00), and SOLX (m = 0.68)