A NOVEL TECHNIQUE FOR LONG-TERM VASCULAR ACCESS IN THE UNRESTRAINED RAT

A new system for long-term vascular access in the unrestrained rat (n = 380) is described that combines low cost with high reliability and f ree movement. It consists of a polyurethane catheter that is placed in the right atrium via the external jugular vein. A leather harness is applied to the animal and the catheter passed subcutaneously to the ne ck into the harness. The harness is connected to the outside of a swiv el joint via a silicone tube in which the catheter runs. The catheter is connected to the inside of the swivel. The swivel is a modified con ventional 5-mL glass syringe and is positioned in ball bearings and Jo hnson joint. Swivel, ball bearings, and the Johnson joint are counterb alanced and can move up and down. With this system all catheter functi oned well until they were electively removed after 28 days. Four cathe ter dislocations resulted from harness failure and three from a twiste d catheter. Seven cases of septicemia and eight of thrombosis cccured. All animals gained weight (3.53 +/- 0.37 [SEM] g/d) during the time t he system was in place. The entire apparatus is simple and inexpensive to construct. The rotary portion of the swivel and the Johnson joint avoid twisting of the catheter, and the counterbalance enables the ani mal to move up and down. The low thrombogenicity of polyurethane furth er reduced complications. This system reduces stress for the animal du ring long-term investigations.