Human Plasma
Collect blood into a pre-chilled vacutainer (lavender top) containing EDTA as the anti-coagulant. Avoid gross hemolysis or lipemia. Immediately add 150 µl of ready-to-use aprotinin solution (Sigma #A6279). Mix by gently rocking the tube and then immediately centrifuge at 1500 x g for 15 minutes in a refrigerated centrifuge set at 4o C. Quickly transfer the clear plasma to a labeled 12 x 75 mm polypropylene tube, held on ice. Immediately acidify the plasma by the addition of 50µl of 1N HCL per one ml of plasma. Mix by inversion and immediately store at -80o C until time of assay.
N.B. Heparin is unsuitable as an anticoagulant for this analysis.
The LINCO radioimmunoassay is a direct measurement of the biologically active form of ghrelin with the octanoyl group on Serine 3. The assay requires 100 ul of plasma in duplicate or 200 ul for one determination.
Suggested blood sample size: 3 ml
