A Contribution to the Physiology of the Perilymph Part I: The Origins of Perilymph

Abstract

Perilymph may as a first approximation be considered an ultrafiltrate of blood. Under quasi-stationary conditions there is a balance of concentrations of nonproteinbound low molecular weight substances in the blood and perilymph, the blood concentration being the governing factor. The rate of equilibration of such substances depends on the exchange rate of perilymph, which may be characterized by τ, the “cochlear half life.” In guinea pigs the mean cochlear half life is ten min, which means that half the perilymphatic volume (8 μl) is exchanged every ten min. It appears most probable that the cells of the organ of Corti (like all other epithelial organs) are metabolically supplied from their base, i.e., from the perilymph. The oxygen supply via the perilymph amounts to 0.1 nM/min, whereas the oxygen supply via the endolymph (equal τ assumed) would only be 1.6% of the perilymphatic supply. The glucose concentration of the perilymph does not constitute a limiting metabolic factor.