Cochlear microcirculation. Effect of adrenergic agonists on arteriole diameter.
We used intravital fluorescent microscopy coupled with computerized video image processing to examine the cochlear microvasculature. In Mongolian gerbils the bulla was opened ventrally and a small window was made in the second turn of the cochlea. After fluorescein isothiocyanate-dextran administration, the radiating arterioles were video-recorded under X675 magnification. Computer determinations of arteriolar response to norepinephrine bitartrate (mixed alpha 1/alpha 2 agonist), phenylephrine hydrochloride (alpha 1 agonist), and UK 14,304 tartrate (alpha 2 agonist) were made at multiple dose levels over time. Findings were consistent with arteriolar constriction in response to alpha-adrenergic stimulation. The presence of alpha 1 and alpha 2 receptors was established, and a predominance of alpha 2 receptors in the cochlea was suggested.
Carrasco
V N
VN
Division of Otolaryngology-Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill.
Prazma
J
J
Faber
J E
JE
Triana
R J
RJ
Pillsbury
H C
HC
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D001160:Arterioles / Q000187:drug effects; D000068438:Brimonidine Tartrate; D003051:Cochlea / Q000098:blood supply* / Q000294:innervation; D005849:Gerbillinae; D007091:Image Processing, Computer-Assisted; D008856:Microscopy, Fluorescence; D009638:Norepinephrine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000502:physiology; D014743:Videotape Recording
D000316:Adrenergic alpha-Agonists; D011810:Quinoxalines; D011942:Receptors, Adrenergic, alpha; D010656:Phenylephrine; D000068438:Brimonidine Tartrate; D009638:Norepinephrine