Project: Research project

Project Details


This investigation is concerned with the mechanisms that control
blood flow in the cochlea, the degree or magnitude of such
control, and the physical locations and effectors of the control.
The nature of the blood-perilymph and blood-endolymph barriers
are of additional interest as is the influence of the sympathetic
nervous system on the cochlear blood supply. In-vivo blood flow
velocity and blood vessel diameters are to be measured using
light microscopic techniques. Analog and digital techniques will
allow quantification of flow and vessel diameter changes for
altered systemic blood pressure, cervical sympathetic ganglion
electric stimulation, CO2 and O2 exposure, osmotic agents, and
intense sound. Extensive use will be made of fluorescence
microscopy using flurescein-isothiocyanate-labeled dextran and
fluroescently labeled red blood cells. The dyes will be excited by
xenon light epl-illumination or transillumination and recorded by
an image intensified video camera and recording system.
Quantitative analysis of cochlear vasculature will be
accomplished by digital image processing techniques. Laser
Doppler flowmetery will be used to determine cochlear blood
flux changes and studies will be carried out to enlarge the
understanding of the performance of this instrumentation.
Expanded knowledge of laser-Doppler flowmetry will help bring
this instrumentation closer to the possible future clinical
application for the measurment of inner ear perfusion. Laser-
Doppler flowmetry will be examined in experiments deriving
comparative analytical measures of functional changes in
cochlear blood flow which are assessed by hydrogen clearance (to
measure regional blood flow), by oxygen sensitive
microelectrodes (to measure intracochlear pO2), and from
compound action potential responses (to test inner ear function).
Autoregulation in the inner ear will be investigated by physically
controlling systemic blood pressure with the aid of an
extracorporeal blood recirculation system. The ultimate goal of the research is to determine the factors
that influence cochlear microcirculation and the effect that
circulation changes have on the inner ear. The studies will help
us to understand normal homeostasis of the inner ear and clarify
the role that microcirculation has in sudden deafness, fluctuant
hearing, sound-induced hearing loss, and Meinere's disease.
Effective start/end date5/1/776/30/92


  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health


  • Medicine(all)
  • Neuroscience(all)

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