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 ± S.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.
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