Intravenous infusion system for chronic drug administration in unrestrained rats

This paper describes a system for long-term intravenous infusion studies in relatively unrestrained rats. It has the advantage of allowing continual 24 hr studies to be run without the problems of having the infusion cable tangle or interfere with the normal activity of the rats, and most of the components are either easily made or readily available from commercial sources. The apparatus itself incorporates the features of several reported chronic infusion systems using modifications to produce a feed-through swivel and infusion cable which can be adapted to a wide range of experimental chambers. In addition, a skull implant is described which minimizes the restraining features inherent in harnesses and provides a secure link between the rat and the infusion cable. The implant mates directly with the infusion cable and is readily detachable. The entire system is inexpensive and requires a minimum of construction.