Induced hypocalcaemia by Na2EDTA infusion.: A review

Disodium ethylenediaminetetraacetate (Na(2)EDTA) has been used in infusion studies in cows and other species for more than 35 years, primarily for the induction of hypocalcemia as a model for milk fever. This paper reviews such studies and discusses blood calcium kinetics, toxicology, changes in various blood parameters and the effect on blood circulation, cardiac function and smooth muscle motility in the gastro-intestinal tract and in the pregnant uterus. It is concluded that Na(2)EDTA infusion may serve as a valid model for spontaneous hypocalcemia. However, experimental results may vary with factors such as the choice of method for blood total calcium analysis, and the rate of EDTA infusion. Standardization of these and certain other experimental conditions may greatly improve the comparability of results obtained in EDTA infusion studies. For cows, an infusion rate of 1.2 ml/kg/h of a 5% (w/v) solution, corresponding to 0.25 mmol/kg/min, has been suggested as a standard infusion.