A direct vasoconstrictor effect of mannitol on the renal artery

The direct effect of mannitol on the renal artery was studied using spiral cut strips of canine renal arteries. Spiral strips were equilibrated in Krebs-Henseleit bicarbonate buffer at 37 degrees C. The strips contracted when challenged with increasing doses of mannitol. The force of contraction was directly proportional to the dose of mannitol used. Vasoconstriction is a direct effect of mannitol on the renal artery in the dose range of 10 to 70 milligrams per milliliter. This observation may explain some of the seemingly contradictory data which have accumulated in studies using mannitol.