Desmecht D J, Linden A S, Godeau J M, Lekeux P M
Department of Physiology, Faculty of Veterinary Medicine, University of Liege, Belgium.
Comp Biochem Physiol A Physiol. 1995 Feb;110(2):115-30. doi: 10.1016/0300-9629(94)00156-n.
Physiological studies of the effects of Ca2+ withdrawal using Na2EDTA have been conducted with the prior basic assumption that Na2EDTA-specific direct or indirect effects on the functions under study were negligible. The present study aimed at providing unequivocal confirmation of such assumption by establishing the pattern of response of blood constituents to intravenous infusions of Na2EDTA in calves. Na2EDTA infusion in calves allowed effective chelation of blood Ca2+, leading to a progressive hypocalcemia. Magnesium levels remained constant and concentrations of other ions (Na+, K+, Pi, H+, HCO3-), although significantly altered (P < or = 0.0001), remained within the normal range. Comparison of enzymes, urea, and creatinine changes precluded renal, hepatic, or muscular parenchymatous damages as being the cause of dysfunctions in the context of Na2EDTA-induced hypocalcemia. It was not possible, however, to standardize the Na2EDTA infusion characteristics (flow, volume) to obtain previsible Ca2+ decay in different animals. Conversely, monitoring of systemic arterial pressure (SAP) offered a precious tool to estimate the degree of hypocalcemia reached. Infusion rate must, therefore, be manipulated using careful on-line monitoring of SAP to obtain an experimental range of Ca2+ as large as possible. It was concluded that physiological data collected during Na2EDTA perfusions can be reliably discussed in terms of Ca2+ dependence rather than in terms of either Na2EDTA toxicity, electrolytes maladjustment, acid-base imbalance, impaired blood oxygenation, or hepatic, renal, myocardic, or skeletal muscle damages.
使用乙二胺四乙酸二钠（Na2EDTA）进行钙离子撤除效应的生理学研究时，预先有一个基本假设，即Na2EDTA对所研究功能的特异性直接或间接影响可忽略不计。本研究旨在通过确定犊牛静脉输注Na2EDTA后血液成分的反应模式，明确证实这一假设。在犊牛中输注Na2EDTA可有效螯合血液中的钙离子，导致渐进性低钙血症。镁水平保持恒定，其他离子（Na+、K+、Pi、H+、HCO3-）的浓度虽有显著变化（P≤0.0001），但仍在正常范围内。对酶、尿素和肌酐变化的比较排除了肾脏、肝脏或肌肉实质损伤是Na2EDTA诱导的低钙血症情况下功能障碍的原因。然而，无法标准化Na2EDTA的输注特性（流速、体积）以在不同动物中获得可预测的钙离子衰减。相反，监测体循环动脉压（SAP）提供了一个宝贵的工具来估计达到的低钙血症程度。因此，必须通过仔细在线监测SAP来控制输注速率，以获得尽可能大的钙离子实验范围。得出的结论是，在Na2EDTA灌注期间收集的生理学数据可以可靠地根据钙离子依赖性进行讨论，而不是根据Na2EDTA毒性、电解质失调、酸碱失衡、血液氧合受损或肝脏、肾脏、心肌或骨骼肌损伤进行讨论。
