Measurement of cochlear blood flow: intravital fluorescence microscopy.
A technique is described for directly observing in vivo cochlear microvasculature in the gerbil for physiologic and experimentally induced changes in vessel diameter and blood flow velocity. Measurements are made from computer processed video images of surgically exposed microvessels. These images are obtained using intravital fluorescence microscopy (IFM) with epi-illumination. The Mongolian gerbil is an ideal animal model for circulatory studies of the inner ear. It has a stable heart rate and blood pressure under urethane/alpha-chloralose anesthesia and its cochlea is surgically accessible. A window is created over the feeding artery (anterior inferior cerebellar artery) and over the stria vascularis of the second turn of the cochlea, atraumatically exposing radiating arterioles and strial capillaries. Our system of IFM provides images that are videorecorded, digitally analyzed with a computer image processor, and enhanced according to the type of measurement desired. Velocity measurements are obtained by tracking plasma gaps or single fluorescent labeled red blood cells through successive frames of the videorecorded images. This experimental technique allows us to analyze circulatory responsiveness to a variety of vasoactive drugs administered regionally to the cochlea in concentrations not affecting systemic circulation.
Prazma
J
J
Division of Otolaryngology/Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill 27599.
Carrasco
V N
VN
Garrett
C G
CG
Pillsbury
H C
HC
D000818:Animals; D003051:Cochlea / Q000098:blood supply*; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000502:physiology; D016650:Fluorescein-5-isothiocyanate; D005452:Fluoresceins; D005456:Fluorescent Dyes; D005849:Gerbillinae; D007202:Indicators and Reagents; D008856:Microscopy, Fluorescence / Q000379:methods*; D010477:Perfusion / Q000379:methods; D012039:Regional Blood Flow; D012965:Sodium Chloride / Q000494:pharmacology; D013861:Thiocyanates
D005452:Fluoresceins; D005456:Fluorescent Dyes; D007202:Indicators and Reagents; D013861:Thiocyanates; D012965:Sodium Chloride; D016650:Fluorescein-5-isothiocyanate; C007740:fluorexon