Cochlear blood flow. The effect of six hours of noise exposure.

The effect of six hours of high-frequency, high-intensity noise exposure on cochlear blood flow (CoBF) was investigated in adult gerbils. The CoBF was measured by microsphere-surface preparation methods. Intracardiac injection of the microspheres (diameter, 11.1 microns; Dupont/New England Nuclear Research Products, Boston) was performed in the last few minutes of the sixth hour of continuous noise exposure, and reference blood was withdrawn from the iliac artery at a rate of 0.165 mL/min. The number of microspheres in the investigated tissue was assessed by direct counting under a microscope. The number of microspheres in the reference blood was counted by a Coulter counter. These experiments have shown that CoBF at the end of six hours of continuous noise exposure does not significantly differ from the CoBF in control animals.