Effects of acute and chronic hypertension on the labyrinthine barriers in rat

Citation
I. Mosnier et al., Effects of acute and chronic hypertension on the labyrinthine barriers in rat, HEARING RES, 151(1-2), 2001, pp. 227-236
Citations number
35
Categorie Soggetti
da verificare
Journal title
HEARING RESEARCH
ISSN journal
03785955 → ACNP
Volume
151
Issue
1-2
Year of publication
2001
Pages
227 - 236
Database
ISI
SICI code
0378-5955(200101)151:1-2<227:EOAACH>2.0.ZU;2-D
Abstract
Hearing loss. vertigo, and tinnitus have been related to arterial hypertens ion. The aim of the present work was to study the permeability of the blood -perilymph and of the labyrinthine barrier, between endolymph and perilymph , to small molecules during chronic and acute hypertension. Experiments wer e performed in normotensive Wistar-Kyoto (WKY) and spontaneously hypertensi ve rats (SHR). Acute hypertension was induced by phenylephrine. Perilymph w as sampled from the first turn of the scala vestibuli and the Na, K, urea, and radioactive concentrations (C-14-urea and H-3-mannitol) were measured. In another experimental set, the endocochlear potential was recorded from t he basal turn of scala media, before and after phenylephrine injection. The composition of the perilymph and the kinetic constants for C-14-urea and 3 H-mannitol were similar in WKY and SHR, and not modified after acute hypert ension. In endolymph, the endocochlear potential in SHR (+80 +/- 2.7 mV, n = 24) was lower (P < 0.001) than in WKY (+98 +/- 1.5 mV, n = 29). The endoc ochlear potential was decreased by 40 mV during acute hypertensive peak in seven out of 19 WKY but not in SHR rats (n = 13). In conclusion, chronic or acute hypertension did not severely alter the permeability to small molecu les of the blood-perilymph barrier. The relationship between the low endoco chlear potential and hypertension in SHR remains to be evaluated. After acu te hypertensive peak, the presence of vascular protective mechanisms in the cochlea could account for the stable endocochlear potential recorded in SH R and 60% of normotensive rats. (C) 2001 Elsevier Science B.V. All rights r eserved.