Glucose Utilization of the Rat Vestibular End Organs: A Quantitative 2-Deoxyglucose Study

Abstract

The local metabolic rate of glucose utilization (LMRglc) for the rat vestibular end organs was determined with a modification of the [14C]deoxyglucose method. Data are expressed as micromoles per 100 g per minute +/- SEM. Results indicate that the LMRglc is similar within the utricle (40.3 +/- 3.2) and saccule (41.2 +/- 5.5) and significantly higher than that for the superior (20.1 +/- 2.9), posterior (25.4 +/- 2.0), or lateral canal (22.0 +/- 2.6) ampullae. These differences in LMRglc may be related to differences in the ratios of sensory to nonsensory cells, dark cell distributions, response to acoustic stimulation, or activity levels during the experimental period. Given the high blood flow rates reported for the vestibular end organs by Lyon and coworkers, a much higher LMRglc was expected. Together, these data would suggest that delivery of metabolites is not a primary regulating force for vestibular blood flow. Instead, the primary reason for a high blood flow rate may be waste removal, the maintenance of pH, ion balance, and/or temperature.

Utricular hypofunction in patients with type 2 diabetes mellitus

“…The different responses of the two end organs, otoliths and semicircular canals, in early stages of diabetes mellitus could be related to their metabolic and vascular characteristics. In murine models, evaluation of the local metabolic rate of glucose utilisation has shown similar results for the utricle and saccule, which were significantly higher than that for the superior, posterior, or lateral canal ampulla 18 . Compared to the posterior canal ampulla, the rat utricular macula is similar with respect to neuroepithelial volume, capillary surface area and blood flow, but the capillary diameter is smaller and the capillary length is greater 19 .…”

Semiquantitative Vestibulotoxicity to Subablative and Ablative Treated Gerbil Cristae Using Gentamicin or Streptomycin

“…These findings suggest that this higher linear density in posterior crista sensory cells might cause the different tolerance to ototoxic drugs. Olds and Lyon [15] concluded that the local metabolic rate of glucose utilization for the rat vestibular endorgans is similar with the utricle and saccule and significantly higher than that of for the superior, posterior, or lateral canal ampullae. Lyon and Jensen [11] asserted that blood flow to all of the vestibular endorgans from rats is similar.…”