Bell D N, Spain S, Goldsmith H L
McGill University Medical Clinic, Montreal General Hospital Research Institute, Quebec, Canada.
Biophys J. 1989 Nov;56(5):829-43. doi: 10.1016/S0006-3495(89)82729-8.
The effect of shear rate on the adenosine diphosphate-induced aggregation of human platelets in Poiseuille flow was studied using the method described in part I (Bell, D.N., S. Spain, and H.L. Goldsmith. 1989. Biophys. J. 56:817-828). The rate and extent of aggregation in citrated platelet-rich plasma were measured over a range of mean transit time from 0.2 to 8.6 s and mean tube shear rate, G, from 41.9 to 1,920 s-1. At 0.2 microM ADP, changes in the single platelet concentration with time suggest that more than one type of platelet-platelet bond mediates platelet aggregation at physiological shear rates. At low G, a high initial rate of aggregation reflects the formation of a weak bond of high affinity, the strength of which diminishes with time. Here, the fraction of collisions yielding stable doublets, the collision efficiency, reached a maximum of 26%. The collision efficiency decreased with increasing G and was accompanied by a progressive delay in the onset of aggregation. However, the gradual expression of a more shear rate-resistant bond at high shear rates and long mean transit times produced a subsequent increase in collision efficiency and a corresponding increase in the rate of aggregation. Although the collision efficiencies here were less than 1%, the high collision frequencies were able to sustain a high rate of aggregation. At 0.2 microM ADP, aggregate size generally decreased with increasing G. At 1.0 microM ADP, aggregate size was still limited at high shear rates even though the rate of single platelet aggregation was much higher than at 0.2 microM ADP. Platelet aggregation was greater for female than for male donors, an effect related to differences in the hematocrit of donors before preparing platelet-rich plasma.
采用第一部分所述方法（Bell, D.N., S. Spain, and H.L. Goldsmith. 1989. Biophys. J. 56:817 - 828）研究了剪切速率对泊肃叶流中人类血小板二磷酸腺苷诱导聚集的影响。在一系列平均通过时间从0.2至8.6秒以及平均管剪切速率G从41.9至1920 s⁻¹的条件下，测定了枸橼酸化富血小板血浆中的聚集速率和程度。在0.2微摩尔/升二磷酸腺苷时，单个血小板浓度随时间的变化表明，在生理剪切速率下，不止一种类型的血小板 - 血小板键介导血小板聚集。在低剪切速率G时，较高的初始聚集速率反映了高亲和力弱键的形成，其强度随时间减弱。在此，产生稳定双联体的碰撞分数，即碰撞效率，最高达到26%。碰撞效率随G的增加而降低，并伴随着聚集起始的逐渐延迟。然而，在高剪切速率和长平均通过时间下逐渐出现的更抗剪切速率的键，导致碰撞效率随后增加以及聚集速率相应增加。尽管此处的碰撞效率小于1%，但高碰撞频率能够维持较高的聚集速率。在0.2微摩尔/升二磷酸腺苷时，聚集体大小通常随G的增加而减小。在1.0微摩尔/升二磷酸腺苷时，即使单个血小板聚集速率远高于0.2微摩尔/升二磷酸腺苷时，在高剪切速率下聚集体大小仍受到限制。女性供体的血小板聚集比男性供体更明显，这种效应与制备富血小板血浆前供体血细胞比容的差异有关。
