Mannitol and dextran increase cochlear blood flow in normotensive and spontaneously hypertensive rats.

Pharmacologic treatments for otopathologies of possible vascular origin are aimed at enhancing vascular transport and are intended to increase cochlear blood flow (CBF). In the current study, normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHRs) were given intravascular infusions of mannitol (20%), dextran 70 (6%), or control saline. In general, the results clearly indicate that both osmotic agents effectively increase CBF, as measured by laser Doppler flowmetry. However, the mechanism of action of these agents is less clear.