Heparin or EDTA; anticoagulant of choice in free radical estimation?

Kuldeep Mohanty, Swetasmita Mishra, Jhumur Pani, Tarannum Hasan, Abhishek Purohit, Subhadra Sharma, Rima Dada

Abstract
Physiological levels of reactive oxygen species (ROS) are needed for various normal processes like cellular immunity, sperm function, capacitation, acrosome reaction, proper embryonic development and implantation, cell signalling, DNA repair activation and gene transcription. Hence anything that creates imbalance in the ROS homeostasis would affect these essential physiological processes. Heparin is a sulfated anionic glycosaminoglycan widely used as an anticoagulant in conditions such as acute coronary syndrome, atrial fibrillation, deep-vein thrombosis and pulmonary embolism, cardiopulmonary bypass for heart surgery and hemofiltration. Ethylenediaminetetraacetic acid (EDTA) is a widely used anticoagulant which is also used in medical conditions like heavy metal poisoning for chelation therapy. To measure the ROS levels in the whole blood we employed a simple chemiluminescence assay using luminol as a chemiluminescent probe. To avoid clotting of blood while estimating free radical levels we used heparin and EDTA as anticoagulants. We observed a significant difference in ROS levels between the two readings using heparin and EDTA. We wish to state that though heparin and EDTA are used as anticoagulants they cause a marked reduction (false low) in the readings due to their antioxidant properties. EDTA caused a much more drastic and significant decline in ROS levels as compared to heparin. Thus in clinical setting they should be used with caution; after assessment of ROS levels so that the redox sensitive physiological reactions may not be impaired and it may not decrease rate of transcription of several genes.

Key words: Anticoagulant; Antioxidant; EDTA; Free radicals; Heparin; Superoxides