Bio-Rad Rat Diabetes Assays - Manual (Page 19)

17
Protease Inhibitors
In general, diabetes biomarkers are detectable in EDTA-treated plasma.
Freezing plasma immediately after preparation and keeping samples
frozen until use should provide adequate protection from degradation.
However, users may choose to add protease inhibitors as a
precautionary measure.
Note: Protease inhibitors are recommended for use with plasma samples
only, not with serum.
Either protease inhibitors may be added to samples at the time of blood
collection (see protocol in the Appendix) or blood samples may be
collected directly into a BD P800 collection tube (Becton-Dickinson,
catalog #366420 or #366421).
Note: BD P800 tubes are not designed for use with mouse samples;
therefore protease inhibitors, if required, should be added at the point of
blood collection.
Plasma
K
2
EDTA-treated plasma is acceptable as long as the sample is immediately
frozen upon collection. Avoid using heparin-treated plasma as it may absorb
certain soluble proteins. Avoid using hemolyzed samples as this may lead to
false positive results.
1. Draw whole blood into collection tubes containing anticoagulant.
2. If desired, add protease inhibitors (see protocol in the Appendix).
3. Invert tubes several times to mix with either the anticoagulant or the
protease
inhibitors.
4. Perform centrifugation at 1,000 x g for 15 min at 4°C and transfer the
plasma to a clean polypropylene tube.
5. To completely remove platelets and precipitates, centrifuge again at
10,000 x g for 10 min at 4°C. Alternatively, filter the samples with a
0.8/0.2 μm dual filter to prevent instrument clogging.