Reduction of Lactate Production By Phospholipase C Inhibition in Cold Stored Platelets

Introduction: Anaerobic glycolysis and resultant lactic acid accumulation have been shown to impair platelet function during cold storage. The goal of current study is to understand the contribution of phospholipase C (PLC) activity to glucose utilization in cold stored platelets.

Methods: Healthy human platelets were stored in 35% plasma and 65% platelet additive solution (PAS) at 4^oC for 15 days after PLC inhibitor (U73122 in 1% dimethyl sulfoxide (DMSO)). Mini aliquot storage bags (BCSI) were used to store platelets in PAS. An iSTAT blood analyzer (Abbott Point of Care) using CG4+ and CHEM8 analysis cartridges measured levels of glucose and lactate values on days 1 – 15 of storage. Five groups were included: control, DMSO vehicle, and three doses of U73122: 10, 20, and 50 µM.

Results: The mean basal level (BL) of lactic acid in the PAS was 0.31 ± 0.01 mM in control and DMSO vehicle groups on the storage day 1 and increased on day 15 of storage to 1.67 ± 0.14 mM in control (5.4-fold increase) and 1.83 ± 0.18 mM in vehicle (6-fold increase). However, lactic acid level only slightly increased to 0.96 ± 0.06 mM, 0.62 ± 0.07 mM, and 0.51 ± 0.05 mM in 10, 20, and 50 µM U73122 groups, respectively, after storage for 15 days. The BL glucose in PAS was 29 ± 0.92 mg/dl in control and DMSO vehicle groups, decreasing to 12.75 ± 2.44 mg/dl (control) and 12.14 ± 2.14 mg/dl (vehicle) after 15 days. Only mild decreases in glucose were observed 15 days after U73122 treatments (24.4 ± 1.47 mg/dl, 24.4 ± 1.94 mg/dl, and 25.2 ± 1.3 mg/dl in 10, 20, and 50 µM, respectively).

Conclusion: The dose-dependent decrease in glucose usage and lactate production with PLC inhibitor U73122 indicate that anaerobic glycolysis is being inhibited in these cold-stored platelets. This suggests that PLC may be a potential therapeutic target to alleviate acidosis and platelet storage lesions.

DoD disclaimer: The views expressed in this abstract are those of the author(s) and do not reflect the official policy or position of the U.S. Army Medical Department, Department of the Army, DoD, or the U.S. Government.