Kuwashima Y, Aoki K, Kohyama K, Ishikawa T
Department of Experimental Pathology, Cancer Institute, Tokyo.
Jpn J Cancer Res. 1990 Jun-Jul;81(6-7):607-12. doi: 10.1111/j.1349-7006.1990.tb02616.x.
In order to investigate the role of blood platelets in regenerative proliferation of hepatocytes in vivo, partial hepatectomy was carried out under conditions of severe thrombocytopenia achieved by X-irradiation and the time-dependent degree of hepatocyte regeneration was measured as labeling index (LI) after 3H-thymidine injection. LI values reached a maximum 36 h after hepatectomy performed 7 days subsequent to a whole-body irradiation of 7.5 Gy, although the maximum rate was found to be only about one-third of that found in unirradiated control rats. At this time point, the number of peripheral blood platelets was decreased to about 2% of that of unirradiated controls and bone marrow megakaryocytes were virtually undetectable. A decrease of LI, similar to that found for the whole-body irradiation in degree, was also observed after local irradiation of the liver with the same dose but without an apparent decrease in platelets. When whole-body irradiation was performed with the liver shielded, under which conditions the numbers of blood platelets decreased to about 8% of the control levels, almost no decrease in LI was found. The results thus suggest that the observed inhibition of hepatocyte regeneration was directly due to liver irradiation and that depletion of blood platelets itself does not interfere with the regeneration process, providing evidence against a dominant role of the platelets in the regeneration as proposed by other authors.
为了研究血小板在体内肝细胞再生增殖中的作用，在通过X射线照射造成严重血小板减少的条件下进行部分肝切除术，并在注射³H-胸腺嘧啶核苷后，将肝细胞再生的时间依赖性程度作为标记指数（LI）进行测量。在全身照射7.5 Gy后7天进行肝切除术后36小时，LI值达到最大值，尽管发现最大速率仅为未照射对照大鼠的约三分之一。在这个时间点，外周血血小板数量减少到未照射对照的约2%，骨髓巨核细胞实际上无法检测到。在用相同剂量局部照射肝脏后，也观察到LI降低，其程度与全身照射相似，但血小板没有明显减少。当在肝脏屏蔽的情况下进行全身照射时，在此条件下血小板数量减少到对照水平的约8%，几乎没有发现LI降低。因此，结果表明观察到的肝细胞再生抑制直接归因于肝脏照射，并且血小板自身的消耗并不干扰再生过程，这为反对其他作者提出的血小板在再生中起主导作用提供了证据。
