The effect of anti-diuretic hormone on the endolymphatic sac of the inner ear |
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| Authors: | Hidetaka Kumagami Hubert Loewenheim Eric Beitz Karen Wild Heinz Schwartz Kimihiro Yamashita Joachim Schultz Jacques Paysan Hans-Peter Zenner J. P. Ruppersberg |
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| Affiliation: | (1) Department of Otorhinolaryngology, University of Tübingen, Silcherstrasse 5, D-72076 Tübingen, Germany e-mail: peter.ruppersberg@uni-tuebingen.de, DE;(2) Institute of Physiology, University of Tübingen, Gmelinstr. 5, D-72076 Tübingen, Germany, DE;(3) Faculty of Chemistry and Pharmacy, University of Tübingen, Auf der Morgenstelle 8, D-72076 Tübingen, Germany, DE;(4) Department of Pharmacology, Nagasaki University School of Medicine, 1-12-4 Sakamoto, Nagasaki 852, Japan, JP;(5) Max-Planck Institute for Biological Development, Spemannstr. 36, D-72076 Tübingen, Germany, DE |
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| Abstract: | The anti-diuretic hormone vasopressin (AVP) regulates water excretion from the kidney by increasing the water permeability of the collecting duct. AVP binds to V2-receptors and induces the translocation of aquaporin-2 water channels (AQP-2) into the apical plasma membrane of principal cells. By this mechanism AVP controls water reabsorption in the kidney. The effects of AVP on the endolymphatic sac (ES) of the inner ear, which is thought to mediate reabsorption of endolymph, were investigated. Both the V2-receptor and the AQP-2 water channel were found to be expressed in the ES epithelium. In the ES AVP binds to receptors most probably of the V2-subtype. Application of AVP to organotypically cultured ES inhibits membrane turnover in ribosomal-rich cells of the ES epithelia, which is thought to mediate translocation of AQP-2 into the surface membrane. This suggests that AVP has contrasting effects in the inner ear and kidney, which may be physiologically useful for maintaining endolymphatic pressure during severe hypovolemia. Animal experiments show that AVP causes endolymphatic hydrops after systemic application to guinea-pigs, which suggests a causal role for the increased AVP levels found in humans suffering from Ménière’s disease. Received: 3 July 1998 / Accepted: 13 July 1998 |
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| Keywords: | Anti-diuretic hormone Aquaporin AVP Endolymphatic hydrops Endolymphatic sac Inner ear Morbus Ménière Vasopressin V2-receptor |
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