Active uptake of serotonin as viability parameter of stored platelets.

The platelet-plasma serotonin (5-HT) exchange in different apheresis products and platelet concentrates (PCs) from buffy coats was studied for quality control over a period of 7 days. In PCs with steadily decreasing pH due to inappropriate gas exchange the platelet 5-HT concentration increases significantly (> 10% positive netto uptake) during the 1st day of storage. Thereafter platelet serotonin drops rapidly with t1/2 = 1 day at pH < 6.5, but platelet counts were constant and 5-HT uptake was inhibited concomitantly. Plasma 5-HT increases as pH decreases. This can be enforced by competitive inhibition of serotonin uptake due to imipramine which also moderates the total 5-HT loss. However, in PC with stable pH the operative 5-HT pump keeps steady-state conditions. The efficacy of the transmembrane uptake mechanism can be adequately monitored by the assessment of the 5-HT platelet/plasma ratio as a new platelet viability parameter.

[Enzyme immunoassay for the determination of serotonin in stored platelet concentrates]. / Enzymimmunoassay zur Bestimmung von Serotonin in gelagerten Thrombozytenkonzentraten.

A new enzyme immunoassay (EIA) was applied on measurements of serotonin (5-HT) in stored platelet concentrates (PC). PC were prepared by apheresis of two separators (Cobe, Fresenius) or from buffy coats and stored for a period of 7 days at 22 degrees C and agitating. Measurements were done in pellets and suspension medium (plasma). Detection of 5-HT was specific and sensitive within the bounds of 2 and 1,000 ng/10(9) PLT.

[Comparison of erythrocyte concentrations of ATP, ADP, AMP and 2,3-BPG in storage of five different additive solutions and in serum]. / Vergleich der erythrozytären Konzentrationen von ATP, ADP, AMP und 2,3-BPG bei Lagerung in fünf verschiedenen additiven Lösungen und in Serum.

In this study, we compared the ability of serum and of 5 additive solutions for the liquid storage of red blood cells to preserve the cellular contents of 2,3-BPG and the adenylate nucleotides ATP, ADP and AMP. As to the adenylates, PAGGS-M showed the best results. However, the difference to SAG-M was significant only after 7 weeks. On the other hand, serum appears to be the best medium for the conservation of 2,3-BPG. Between the 1st and 3rd week of storage, the decrease of 2,3-BPG was somewhat slower in PAGGS-M and SAG-M compared with the other 3 additive solutions.

[Oxygen affinity and regeneration capacity of SAG-M and PAGGS-M stored erythrocytes]. / Sauerstoffaffinität und Regenerationsfähigkeit in SAG-M und PAGGS-M gelagerter Erythrozyten.

In order to estimate the leftward shift of the oxygen dissociation curve of hemoglobin following storage of red blood cells (rbc) in the additive solutions SAG-M and PAGGS-M, respectively, we performed blood gas analyses after equilibrating the cells with a gas mixture containing 4% of O2 and 5% of CO2 at pH 7.4 and 37 degrees C. Additionally, we took advantage of these nearly physiological conditions to measure the recovery of the hemoglobin function in vitro. We observed a good correlation between 2,3-BPG and p50 (i.e. the oxygen tension, at which hemoglobin is half-saturated with oxygen). Within the first 3 weeks of storage, the 2,3-BPG content fell to one fifth of its original value, whereas the p50 declined from 26.6 to about 20 mm Hg. Compared to fresh cells, rbc stored for longer than 3 weeks will thus deliver 30% less oxygen to the myocardium. The rbc's ability to restore these parameters remained unchanged throughout 7 weeks of storage.