Effect of insulin on renal vascular escape in normal and diabetic kidney

Renal Vascular Escape was studied in the isolated perfused kidney harvested from diabetic and normal rabbits. Diabetes was induced 3-4 weeks earlier by injecting the animals with 150 mg/kg alloxan IP. To induce vasoconstriction, norepinephrine (10(-6) M) (NOR) was infused to the renal artery for 20 min, during 3 cycles, with intervals of 10 min for drug wash out, with a total duration of 90 min of observation. Administration of NOR induced intense vasoconstriction which was followed by a period of relaxation, in spite of the continued infusion of the adrenergic neurohormone. This was named renal vascular escape (RVE). RVE was present in all control animals but was severely impaired in diabetic kidneys. The administration of insulin (20 mU/ml or 2 mU/ml) to the perfusate promoted a significant blockade of escape (p < 0.001) in normal kidneys, which was time dependent, and only a slight effect in the diabetic group. These data show an interaction between insulin and RVE in normal animals and could point out another defect in diabetes, as related to insulin resistance.