Abstract
The inner ear must maintain a delicate homeostasis to preserve high sensitivity to acoustic and vestibular inputs. Various experimental conditions were imposed upon chinchillas to help identify these homeostatic mechanisms for the inner ear fluids. Radioactive ions (sodium, chloride, and calcium) pass into perilymph more slowly than they pass into cerebrospinal fluid or aqueous humor. The concentration of glucose in perilymph relative to that in serum was found to be quite constant (about 45 per cent) over a wide range of serum values (130-943 mg/dl) generated by continuous intravenous infusion. The transport of albumin into perilymph was very slight after injection of the radioactive protein intravenously. Osmotic agents cause an efflux of water from perilymph into a relatively hypertonic circulating blood, resulting in a secondary elevation of perilymph osmolarity. Recent findings relating to cyclic AMP metabolism and the possible role of this second messenger in the regulation of inner ear fluid metabolism are discussed. A new hypothesis that excess cyclic AMP in the inner ear may be related to endolymphatic hydrops is presented.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 392-396 |
| Number of pages | 5 |
| Journal | American Journal of Otolaryngology--Head and Neck Medicine and Surgery |
| Volume | 3 |
| Issue number | 6 |
| DOIs | |
| State | Published - 1982 |
Bibliographical note
Funding Information:The existence of the inner ear fluids, which modulate neural signals to be transmitted to the brain for sound perception through the cochlea or balance through the vestibular sense organs, is well known. It is also clear that the inner ear must possess remarkably stable homeostatic mechanisms, which are essential for the maintenance of the functional integrity of the inner-ear end organs, despite the fact that the inner ear fluids are under continuous influence of any changes occurring in the surrounding blood and cerebrospinal fluid (Fig. 1). The maintenance of constant chemical composition of body fluids appears to be related to the existence of various barrier systems. These barrier systems are usually ascribed to vascular endothelia and/or epithelia (Fig. 2). It is conceivable that a disturbance of homeostasis may result in sequential changes in chemical composition of the inner Received June 29, 1982. Accepted for publication July 13, 1982. Supported by NIH R01 NS14911-01, NIH Teacher Investigator Award K07 NS00705, NIH EY-1258, and The Deafness Research Foundation. Presented at the Midwinter Research Meeting of the Association for Research in Oto-laryngo\]ogyJ, anuary 18-21, 1982, St. Petersburg Beach, Fla, * Department of Otolaryngology,U niversity of Minnesota Medical School, Minneapolis, Minnesota 55455. t Division of Otolaryngology and Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois. r Department of Ophthalmology, University of Minnesota Medical School. Address correspondencea nd reprint requests to Dr. Iuhn.
Keywords
- Blood-perilymph barrier
- Endolymphatic hydrops
- inner ear fluids