Comparison Of Mean Platelet Survival Time In A Non-Radioisotope Method Calculatend With New Model With Mean Survival Time In CR-51 Methods

Platelet survival time using non-radioisotope method measuring malondialdehyde(MDA) generation stimulated by arachidonate prior to and after intake of aspirin(ASA) and Cr-51 method was measured simultaneously in 18 cases with ITP. In cases with normal platelet survival time MDA generation curve showed linear or the letter-S pattern. On the other hand, all cases with shorter survival time had MDA generation curve with letter-S pattern. To describe the S pattern of MDA generation curve following model was devised on the assumption : 1) ASA inhibits MDA generation in megakaryocytes so that newly produced platelets show impaired MDA generation, 2) ability of MDA generation in platelets exposed to ASA recovers during circulating.where a is the disappearance time of inhibiting effect of ASA on megakaryocyte MDA generation and b is the time necessary for recovery of MDA generation in platelets exposed to ASA. Mean survival time(MST) is calculated by l/λ.The difference of MST between non-radioisotope method and Cr-51 method( gamma model) in 11 cases with MST of less than 4 days in Cr-51 method were 2.9 ± 0.4 days in platelet survival time (PST) at which MDA generation attained to pre-ASA levels, 2.7 ± 0.4 days in MST calculated with linear regression of MDA generation curve and 1.8 ± 0.4(SEM) days in MST calculated by the above model. On the other hand, in cases with MST of more than 4 days in Cr-51 method the difference of MST in both methods were 1.4 ± 0.3(SEM) days in PST, 0.6 ± 0.2 days in linear regression and 0.6 ± 0.2 days when MST was calculated with the above formula.These results suggest that the model reported is so far the better fitting model for the MDA generation curve in cases with normal and shortened platelet survival.