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The inner ear produces a natriuretic hormone
K Qvortrup1, J Rostgaard, N H Holstein-Rathlou
1Department of Medical Anatomy, University of Copenhagen, Panum Institute, Denmark
The American Journal of Physiology
|June 1, 1996
Summary
The endolymphatic sac produces a substance that inhibits sodium reabsorption, potentially mediating cerebral natriuresis and influencing inner ear fluid balance, which may be relevant to Meniere's disease.
Area of Science:
- Inner ear physiology
- Renal function
- Neuroendocrinology
Background:
- Epithelial cells in the endolymphatic sac contain cytoplasmic granules.
- The endolymphatic sac is an extraosseus component of the inner ear situated in the posterior cranial fossa.
Purpose of the Study:
- To investigate the physiological effects of endolymphatic sac extracts.
- To determine if the endolymphatic sac contains an endogenous inhibitor of sodium reabsorption.
- To explore the potential role of the endolymphatic sac in cerebral natriuresis and Meniere's disease pathogenesis.
Main Methods:
- Intravenous infusion of endolymphatic sac extracts into anesthetized rats.
- Administration of dural tissue extracts as a control.
- Monitoring of blood pressure, glomerular filtration rate, lithium clearance, natriuresis, diuresis, and kaliuresis.
Main Results:
- Endolymphatic sac extracts induced significant natriuresis and diuresis.
- No changes were observed in blood pressure, glomerular filtration rate, or lithium clearance.
- Dural tissue extracts showed no physiological effects.
- A minor kaliuresis was noted.
Conclusions:
- The endolymphatic sac contains an endogenous inhibitor of sodium reabsorption, tentatively named saccin.
- The endolymphatic sac may function as a sensory organ or mediator for cerebral natriuresis.
- Saccin may play a role in regulating inner ear fluid homeostasis and the pathogenesis of Meniere's disease.