Department of Microbiology and Parasitology, Universidade Federal de Santa Maria, Brazil.
Vet Parasitol. 2011 May 31;178(1-2):9-14. doi: 10.1016/j.vetpar.2010.12.041. Epub 2011 Jan 11.
Nucleotide and nucleoside-degrading enzymes, such as nucleoside triphosphate diphosphohydrose (NTPDase), 5'-nucleotidase and adenosine deaminase (ADA) are present in the surface membranes of platelets, involved in clotting disturbances of Trypanosoma evansi-infected animals. Thus, this study was aimed at evaluating the activities of these enzymes in platelets of rats experimentally infected with T. evansi. Animals were divided into four groups, according to the level of parasitemia. Blood samples were collected on days 3 (group A: at the beginning of parasitemia), 5 (group B: high parasitemia) and 15 (group C: chronic infection), post-infection. Group D (control group) was composed of non-infected animals for platelet count, separation and enzymatic assays. Animals from groups A and B showed marked thrombocytopenia, but platelet count was not affected in chronically infected rats. NTPDase, 5'-nucleotidase and ADA activities decreased (p<0.05) in platelets from rats of groups A and B, when compared to the control group. In group C, only NTPDase and 5'-nucleoside activities decreased (p<0.001). The correlations between platelet count and nucleotide/nucleoside hydrolysis were positive and statistically significant (p<0.05) in groups A and B. Platelet aggregation was decreased in all infected groups, in comparison to the control group (p<0.05). It is concluded that the alterations observed in the activities of NTPDase, 5'-nucleotidase and ADA in platelets of T. evansi-infected animals might be related to thrombocytopenia, that by reducing the number of platelets, there was less release of ATP and ADP. Another possibility being suggested is that changes have occurred in the membrane of these cells, decreasing the expression of these enzymes in the cell membrane.
核苷酸和核苷降解酶，如核苷三磷酸二磷酸水解酶（NTPDase）、5'-核苷酸酶和腺苷脱氨酶（ADA）存在于血小板的表面膜中，参与了感染锥虫的动物的凝血紊乱。因此，本研究旨在评估实验感染锥虫的大鼠血小板中这些酶的活性。动物根据寄生虫血症水平分为四组。在感染后第 3 天（A 组：寄生虫血症开始时）、第 5 天（B 组：高寄生虫血症）和第 15 天（C 组：慢性感染）采集血液样本。D 组（对照组）由未感染的动物组成，用于血小板计数、分离和酶测定。A 组和 B 组动物表现出明显的血小板减少症，但慢性感染大鼠的血小板计数未受影响。与对照组相比，A 组和 B 组大鼠血小板中的 NTPDase、5'-核苷酸酶和 ADA 活性降低（p<0.05）。在 C 组中，只有 NTPDase 和 5'-核苷酸酶活性降低（p<0.001）。在 A 组和 B 组中，血小板计数与核苷酸/核苷水解之间的相关性呈正相关且具有统计学意义（p<0.05）。与对照组相比，所有感染组的血小板聚集均降低（p<0.05）。综上所述，感染锥虫的动物血小板中 NTPDase、5'-核苷酸酶和 ADA 活性的改变可能与血小板减少症有关，即由于血小板数量减少，释放的 ATP 和 ADP 减少。另一种可能性是这些细胞的膜发生了变化，导致这些酶在细胞膜上的表达减少。
