Simultaneous sampling of blood, bile, and urine in rats for pharmacokinetic studies.

A method for simultaneous serial sampling of blood, bile, and urine from rats is described. Techniques for cannulation of jugular and femoral veins, bile duct, and bladder are described that make serial sampling of these three fluids possible. A saline infusion regimen was developed that prevents dehydration and maintains constant hematocrit values throughout the experiment. Accuracy of timed-samples can be easily controlled along with complete collection of voided urine. This method also allows for economy in terms of cost (number of animals used) and time in pharmacokinetic investigations involving the rat where extensive sampling of blood, bile, and urine are needed. In addition, interanimal variability, which can be quite high in such studies, is avoided by sampling all these three fluids in a single rat. While the kinetic parameters of blood aluminum obtained from this anesthetized animal model compare well with those in unanesthetized rats reported from this laboratory, this method is most useful for comparative studies.