CONTINUOUS INTRAVENOUS-INFUSION IN THE UNRESTRAINED RAT - PROCEDURES AND RESULTS

1 A method of continuous infusion in the unrestrained rat is described , which provides a scientifically acceptable and easily maintained rod ent model for use in toxicological investigations. 2 Sprague Dawley SP F rats had cannulas implanted into the vena cava via the femoral vein, and were continuously infused with physiological saline for a total o f 28 or 90 days. 3 The results indicate that there was no change in bo dy weight, food consumption, clinical observations or clinical biochem istry of infused rats when compared to non-infused rats. There were sm all changes in haematological parameters, however none were toxicologi cally significant. Urinary volume was increased and urinary specific g ravity and osmolality were decreased. At macroscopic and microscopic e xamination there were findings of scar formation associated with the a rea of surgery and minimal irritation in the area of the vena cava whi ch accommodated the cannula. 4 These results indicate that implantatio n of a cannula into the vena cava of a rat and subsequent continuous i ntravenous infusion of physiological saline produces no toxicological adverse effects over a period of 90 days. Consequently, this model can be recommended for the continuous intravenous administration of test substances to rats.