Lopes A A, Maeda N Y, Ebaid M, Chamone D A
Department of Pediatric Cardiology, University of São Paulo, Brazil.
Int J Cardiol. 1990 Aug;28(2):173-8. doi: 10.1016/0167-5273(90)90058-d.
The response of aggregation of platelets to adenosine diphosphate (7.5-120 microM) and collagen (1.25 micrograms/ml) was assessed in whole blood (impedance method) in 10 children with pulmonary hypertension (hematocrit range, 42 to 71%). The response to collagen was normal (9.08 +/- 3.47 vs. 10.36 +/- 1.86 ohms in controls, P = NS) while there was a decreased response to adenosine diphosphate (6.98 +/- 3.83 vs. 11.21 +/- 2.02 ohms, P less than 0.01), in spite of high concentrations of the inducer. Lowering the hematocrit in vitro to 40% with autologous platelet-rich plasma resulted in a rise in the platelet count from 171 +/- 63 to 225 +/- 84 x 10(9) platelets/1 (P less than 0.001) and a significant increase in the response to adenosine diphosphate from 6.98 +/- 3.83 to 9.89 +/- 3.66 ohms (P less than 0.02). As in the baseline condition, high concentrations of adenosine diphosphate were required. The response to collagen did not change significantly. The results indicate that aggregatory response of platelets is relatively preserved in these children. The decreased response to adenosine diphosphate may be a result of a low count and interference of red cells on the accretion of platelets on the electrodes. Because high concentrations of adenosine diphosphate were still required after hemodilution to achieve an aggregatory response close to normal, we speculate that leakage of endogenous adenosine diphosphate from red cells may have accounted for partial activation of the platelets, resulting in a relative refractory state to in vitro stimulation.
采用阻抗法在全血中评估了10例肺动脉高压患儿（血细胞比容范围为42%至71%）的血小板对二磷酸腺苷（7.5 - 120微摩尔）和胶原（1.25微克/毫升）的聚集反应。对胶原的反应正常（与对照组相比，分别为9.08±3.47和10.36±1.86欧姆，P =无显著差异），而对二磷酸腺苷的反应降低（分别为6.98±3.83和11.21±2.02欧姆，P＜0.01），尽管诱导剂浓度很高。用自体富血小板血浆在体外将血细胞比容降至40%，导致血小板计数从171±63升至225±84×10⁹血小板/升（P＜0.001），并且对二磷酸腺苷的反应从6.98±3.83显著增加至9.89±3.66欧姆（P＜0.02）。与基线情况一样，需要高浓度的二磷酸腺苷。对胶原的反应没有显著变化。结果表明这些患儿血小板的聚集反应相对保留。对二磷酸腺苷反应降低可能是血小板计数低以及红细胞对电极上血小板聚集的干扰所致。由于血液稀释后仍需要高浓度的二磷酸腺苷才能使聚集反应接近正常，我们推测红细胞内源性二磷酸腺苷的泄漏可能导致血小板部分活化，从而使其对体外刺激处于相对不应状态。
