Bell D N, Spain S, Goldsmith H L
McGill University Medical Clinic, Montreal General Hospital, Quebec, Canada.
Thromb Haemost. 1990 Feb 19;63(1):112-21.
The effect of red blood cells, rbc, and shear rate on the ADP-induced aggregation of platelets in whole blood, WB, flowing through polyethylene tubing was studied using a previously described technique (1). Effluent WB was collected into 0.5% glutaraldehyde and the red blood cells removed by centrifugation through Percoll. At 23 degrees C the rate of single platelet aggregation was upt to 9 x greater in WB than previously found in platelet-rich plasma (2) at mean tube shear rates G = 41.9, 335, and 1,920 s-1, and at both 0.2 and 1.0 microM ADP. At 0.2 microM ADP, the rate of aggregation was greatest at G = 41.9 s-1 over the first 1.7 s mean transit time through the flow tube, t, but decreased steadily with time. At G greater than or equal to 335 s-1 the rate of aggregation increased between t = 1.7 and 8.6 s; however, aggregate size decreased with increasing shear rate. At 1.0 microM ADP, the initial rate of single platelet aggregation was still highest at G = 41.9 s-1 where large aggregates up to several millimeters in diameter containing rbc formed by t = 43 s. At this ADP concentration, aggregate size was still limited at G greater than or equal to 335 s-1 but the rate of single platelet aggregation was markedly greater than at 0.2 microM ADP. By t = 43 s, no single platelets remained and rbc were not incorporated into aggregates. Although aggregate size increased slowly, large aggregates eventually formed. White blood cells were not significantly incorporated into aggregates at any shear rate or ADP concentration. Since the present technique did not induce platelet thromboxane A2 formation or cause cell lysis, these experiments provide evidence for a purely mechanical effect of rbc in augmenting platelet aggregation in WB.
采用先前描述的技术(1)，研究了红细胞（RBC）、剪切速率对全血（WB）中ADP诱导的血小板聚集的影响，全血流经聚乙烯管。将流出的全血收集到0.5%的戊二醛中，并通过Percoll离心去除红细胞。在23℃时，在平均管剪切速率G = 41.9、335和1920 s-1以及0.2和1.0 microM ADP的条件下，全血中单个血小板的聚集速率比先前在富含血小板血浆(2)中发现的速率高9倍。在0.2 microM ADP时，在流经流管的前1.7 s平均通过时间t内，聚集速率在G = 41.9 s-1时最大，但随时间稳步下降。在G≥335 s-1时，聚集速率在t = 1.7至8.6 s之间增加；然而，聚集体大小随着剪切速率的增加而减小。在1.0 microM ADP时，单个血小板聚集的初始速率在G = 41.9 s-1时仍然最高，在t = 43 s时形成直径达几毫米的含有红细胞的大聚集体。在此ADP浓度下，在G≥335 s-1时聚集体大小仍然受限，但单个血小板的聚集速率明显高于0.2 microM ADP时。到t = 43 s时，没有单个血小板残留，红细胞也未并入聚集体。虽然聚集体大小增加缓慢，但最终形成了大聚集体。在任何剪切速率或ADP浓度下，白细胞都没有明显并入聚集体。由于本技术不会诱导血小板血栓素A2形成或导致细胞裂解，这些实验为红细胞在增强全血中血小板聚集方面的纯机械作用提供了证据。
