Effect of Glycerol on Electrochemical Composition of Endolymph and Perilymph in the Rat

Abstract

Glycerol (2g/kg body weight), or 0.15 M NaCl for control animals, was administered to rats by i.v. injection. the dose was chosen in order to obtain an osmolality increase in plasma of about 15 mosm/l 1 h after the glycerol administration, an increase which is similar to that observed in the human glycerol dehydration test. Endolymph and perilymph were sampled from the basal turn of the cochlea; cerebrospinal fluid (CSF) was sampled from cisterna magna. Plasma osmolality, endocochlear potential, Na and K concentrations in endolymph, perilymph and CSF were determined 1 and 2 h after the glycerol injection. Compared with control animals, glycerol induced an increase in Na and K concentration in perilymph and endolymph, respectively, 1 and 2 h after the glycerol injection. No modification of the endocochlear potential was observed. These results are compatible with an increase in inner ear fluids osmolality induced by glycerol.

Key Words:

• Na K
• endocochlear potential
• osmolarity
• Meniere's disease