Effects of pentoxifylline and nitroprusside on guinea pig cochlear blood flow in relationship to various hematocrit values

Abstract

To understand better the microcirculation in the inner ear in relation to blood viscosity, we examined the effects of pentoxifylline (PXF) and nitroprusside (NP) on cochlear blood flow (CBF) in healthy adult guinea pigs in relationship to various hematocrit (H1) values. There was no correlation between Ht value and the maximum decrease of mean blood pressure after PXF infusion, whereas there was a positive correlation between Ht and the maximum increase in CBF. No such relationship was found after NP infusion. A graph plot of each animal's blood oxygen transport capacity (i.e., Ht/blood viscosity) was found to have a convex form and to increase with a shift of the peak to a higher Ht area after PXF infusion. These findings indicate that a decrease in blood viscosity may improve CBF and increase oxygen transport capacity of blood.

Protective Effects of Pentoxifylline and Nimodipine on Acoustic Trauma in Guinea Pig Cochlea

“…Cochlear blood flow is closely associated with cochlear function. If cochlear blood flow is reduced, the transport of oxygen and nutrients to the inner ear and the removal of metabolites from the inner ear decrease (13,14). Histologic studies often show alterations (e.g., endothelial cellular edema, constriction of the capillaries, unusual spacing of the red blood cells in the cochlear vessels) that are usually associated with decreased circulation (14).…”

“…One potential mechanism of noise-induced hearing loss is vascular pathology in the microcirculation of the cochlea. Several studies have revealed histologic evidence of reduced cochlear blood flow after noise exposure (13). Cochlear blood flow is closely associated with cochlear function.…”

“…Pentoxifylline, a methylxanthine derivative and nonspecific phosphodiesterase inhibitor, is a potent vasodilator and a hemorheologically active drug that reduces blood viscosity and the concentration of serum fibrinogen, stimulates fibrinolysis, exerts other anticoagulant effects, promotes flexibility, and decreases the aggregation of red blood cells and platelets, thereby increasing tissue microcirculation (13,15,16). Pentoxifylline has been used for years to treat peripheral and cerebral vascular diseases.…”