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Anticoagulant effects on plasma coenzyme Q(10) estimated by HPLC with coulometric detection
Peter H Tang1, Michael V Miles, Paul Steele
1Division of Pediatric Neurology, Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA. tangp0@chmcc.org
Background:
The proportion of reduced coenzyme Q(10) (Q(10)H(2)) in total coenzyme Q(10) (TQ(10)), referred to as the Q(10)H(2):TQ(10) ratio, may be used as a possible marker of in vivo oxidative stress. However, the ranges for Q(10)H(2):TQ(10) ratio from previous reports are quite variable. Sample handling and preparation appear to have a profound effect on the stability of Q(10)H(2).
Methods:
Paired tests were used to estimate TQ(10), Q(10)H(2), oxidized coenzyme Q(10) (Q(10)), and Q(10)H(2):TQ(10) ratio in patient samples collected in vacutainers containing heparin or EDTA. Sample tubes were immediately placed on ice and promptly centrifuged. After harvesting plasma, 100 microl of plasma was extracted with 1-propanol and centrifuged. The supernatant was injected directly into a high-performance liquid chromatography (HPLC) system.
Results:
Significantly higher values (p=0.0015) of TQ(10), Q(10)H(2), and Q(10)H(2):TQ(10) ratio were noted in heparinized plasma as compared to EDTA plasma; Q(10) concentrations were lower in heparinized plasma. When vacutainers containing specimen were opened and kept refrigerated, the Q(10)H(2):TQ(10) ratios in heparinized samples were stable over 7 h with variation <3%. Blood Q(10)H(2) in closed heparin vacutainers kept refrigerated was stable up to 24 h.
Conclusions:
Our results indicate that the heparinized plasma is superior to the EDTA plasma in all measurements for coenzyme Q(10).