Darien B J, Potempa J, Moore J N, Travis J
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens 30602.
Vet Res Commun. 1989;13(1):31-46. doi: 10.1007/BF00366851.
Two synthetic substrate assays (fluorometric and chromogenic) were used to measure antithrombin-III (AT-III) activity (residual thrombin activity) in non-medicated and heparin (sodium) treated horses. In 18 non-medicated horses the fluorometric substrate assay (FSA) values were similar to previous reports but they reflected inconsistent trends and larger deviations in the heparin-treated groups (Group 2: 40 and 100 U/kg IV, n = 6; Group 3: 240 U/kg IV, n = 5; Group 4: 80 U/kg IV followed by 160 U/kg SC, n = 8) when compared to the chromogenic substrate assay (CSA) values. The CSA values for the 18 non-medicated horses indicated a higher AT-III activity (lower residual thrombin activity) than the FSA. AT-III activity was quantified in 18 non-medicated horses (29 mg/dl) and compared well with values for humans (30 mg/dl) and dogs (40 mg/dl). Plasma heparin concentrations, determined by the FSA, correlated well with the 'therapeutic range' (1.5 fold to 2.5 fold prolongation of the activated partial thromboplastin time (APTT) normal value) and values reported for humans. The effect of heparin therapy on AT-III activity in four treatment regimens was evaluated. AT-III activity was not significantly affected (with one exception) by a single dose of intravenous (IV) heparin (40 and 100 U/kg) nor by repeated subcutaneous (SC) injections of heparin (240 U/kg). A transient increase in residual thrombin activity was measured 12 h after an intravenous (80 U/kg) injection of heparin. Large doses of heparin (80 U/kg IV followed by 160 U/kg SC) given every 12 h produced a progressive prolongation of the APTT. In this group the APTT remained prolonged 48 h after the last treatment.
采用两种合成底物测定法（荧光法和显色法）来测量未用药及肝素（钠）治疗马匹的抗凝血酶III（AT-III）活性（残余凝血酶活性）。在18匹未用药马匹中，荧光底物测定法（FSA）的值与先前报告相似，但与显色底物测定法（CSA）的值相比，它们在肝素治疗组（第2组：静脉注射40和100 U/kg，n = 6；第3组：静脉注射240 U/kg，n = 5；第4组：静脉注射80 U/kg，随后皮下注射160 U/kg，n = 8）中反映出不一致的趋势和更大的偏差。18匹未用药马匹的CSA值表明其AT-III活性（残余凝血酶活性更低）高于FSA。在18匹未用药马匹中对AT-III活性进行了定量（29 mg/dl），并与人类（30 mg/dl）和犬类（40 mg/dl）的值进行了良好比较。通过FSA测定的血浆肝素浓度与“治疗范围”（活化部分凝血活酶时间（APTT）正常值延长1.5倍至2.5倍）以及人类报告的值具有良好相关性。评估了肝素治疗对四种治疗方案中AT-III活性的影响。单剂量静脉注射（IV）肝素（40和100 U/kg）或反复皮下注射（SC）肝素（240 U/kg）对AT-III活性没有显著影响（有一个例外）。静脉注射肝素（80 U/kg）12小时后测量到残余凝血酶活性短暂增加。每12小时给予大剂量肝素（静脉注射80 U/kg，随后皮下注射160 U/kg）会使APTT逐渐延长。在该组中，最后一次治疗后48小时APTT仍处于延长状态。
