Mannitol diuresis in hemorrhagic hypotension

In anesthetized dogs and cats bleeding to arterial pressures below 50 mm Hg did not cause anuria when infusions of hypertonic mannitol were given at 0.20–0.40 ml/kg·min. In animals infused with isotonic saline, urine flow stopped below 50 mm Hg, but could be re-established by infusion of hypertonic solutions of mannitol, sodium sulfate, or urea. In both groups urine flow finally stabilized at 5–40%, and GFR (CIn) at 2–14% of prehemorrhagic values. CCr(exog)/CIn fell to values below unity in hemorrhagic hypotension in most dogs. In most cats CCr(exog) /CIn was larger than 1.10, and was lowered in hemorrhagic hypotension.