Renal function in chronically catheterized conscious diabetic rats using constant and servo-controlled infusion

1. Infusion experiments were performed on chronically catheterized consciou s rats to assess kidney function before and after the induction of diabetes mellitus with streptozotocin, 2. Two infusion regimens were used, a conventional constant-infusion protoc ol and a novel computer-driven, servo-controlled fluid replacement techniqu e. The latter enables body fluid status to be maintained throughout a study occasion by servo-controlled replacement of spontaneous urinary fluid loss es. 3. The chronically catheterized conscious rat infused using a servo-control led system appears to be the optimum model for a study of diabetic renal fu nction. The conscious preparation circumvents problems associated with anae sthesia and acute surgery. The servo-controlled infusion protocol maintains the altered fluid status of the diabetic condition. Both hyperfiltration a nd polyuria, characteristics of human diabetes often absent in anaesthetize d and/or constantly infused diabetic rats, were seen in all conscious servo -controlled diabetic animals. 4. The new regimen enables a more accurate assessment of renal function in experimental diabetes than with previous protocols. It should prove useful in future studies, particularly those assessing the role of anti-diabetic d rugs on the kidney.