Determination of absolute amounts of heparin and of dextran sulfate in plasma in microgram quantities.

Heparin and dextran sulfates 8000 are separated from citrated plasma by absorption on epichlorohydrin triethanolamine cellulose columns followed by elution with 1.1 and 1.4 mol/L NaCl in 0.05 mol/L glycine-HCl buffer. The eluate is desalted with Sephadex G25-40, dried, and dissolved in water. A 1 microliters sample is applied to an agarose gel slide. After electrophoresis, the slide is fixed and stained with toluidine blue. The sulfated polysaccharide band(s) is identified by relative electrophoretic migration. The total amount of drug is estimated by matching its optical density with that of a band on one of a set of slides with graded amounts of heparin or dextran sulfate. The reaction with toluidine blue measures the total polyelectrolyte, not just the small proportion of the drug with anticoagulant activity. Pooled normal plasma showed a trace of chondroitin and no heparin. Recovery of heparin and hydrogenated dextran sulfate that was added to pooled normal plasma was complete (lowest concentration tested was 10 micrograms/ml); however, recovery for unhydrogenated dextran sulfate declined consistently by 9 micrograms/ml for concentrations below 50 micrograms/ml, setting a limit for its recovery. Plasma samples taken from patients for coagulation tests were examined by this procedure, and in so doing, steps were ascertained to improve the procedure for routine use. Results were compared with values for prothrombin time and activated partial thromboplastin times obtained on the same samples by the clinical laboratory. Because the procedure provides an independent parameter for measurement in patients who have received heparin therapy, insight into different patient responses to the drug is therefore possible. With minor modifications, the procedure can be used for heparans, dermatans, and chondroitins, because it allows identification and microscale quantitation on the basis of charge, molecular weight, and carbohydrate structure.