Summary
The effects of acidic mucopolysaccharide extracted from sea cucumber (Stichopus japonicus Selenka) (SJAMP) on rabbit platelets were studied. Using citrated platelet-rich plasma
(PRP), washed platelets, and formaldehyde fixed platelets from 10 New Zealand white
rabbits, we investigated the effects of platelet inhibitors and various plasma and
its fractions on SJAMP-induced agglutination. It was found that the tracing of platelet
agglutination induced by SJAMP showed a single phase without a lag period. The lowest
concentration of SJAMP required for the agglutination of rabbit platelets was approximately
2 μg/ml, and the magnitude of agglutination induced by SJAMP was concentration dependent.
In 8 out of 10 rabbits, the platelets in PRP were agglutinated by 10 μg/ml of SJAMP.
Platelet inhibitors, such as aspirin, indomethacin, apyrase, antimycin, 2-deoxy-D-glucose
and EDTA did not inhibit the agglutination induced by SJAMP. Washed rabbit platelets
were not agglutinated by SJAMP even though the concentration of SJAMP was raised up
to 50 μg/ml. When rabbit plasma, serum, or 50–60% ammonium sulfate saturated plasma
fraction was added to the reaction mixture, agglutination of washed platelets by SJAMP
was recovered completely. But human plasma or fibrinogen did not have any effect on
the reactivity of washed rabbit platelets to SJAMP. From these data we conclude that
the SJAMP-induced rabbit platelet agglutination is independent of energy metabolism
but requires plasma cofactor(s) other than fibrinogen. The plasma cofactor is present
in 50–60% ammonium sulfate saturated plasma fraction.
Keywords Platelet aggregation - Acidic mucopolysaccharide - Rabbits
