Differences in biochemical composition between perilymph, cerebrospinal fluid and blood plasma in the guinea pig

Abstract

Cochlear perilymph (PL) — a major intralabyrinthine fluid — is considered to play an important role in the auditory function of the inner ear. However, despite numerous studies of the biochemistry and physiology of PL, its formation and composition — derived from cerebrospinal fluid (CSF) versus ultrafiltrate of blood plasma — have long been a controversial subject. This is also true for its metabolic function for the organ of Corti. To elucidate this problem, we systematically investigated a number of essential chemical components (glucose, pyruvate, lactate, sodium, potassium, protein, lactate dehydrogenase) in PL, CSF and blood plasma of anesthetized guinea pigs (Scheibe and Haupt 1985) with due consideration of significant sources of error connected with the sampling procedure, particularly the contamination of PL with CSF (Bergmann et al. 1979; Scheibe et al. 1984). In addition, we have recently analyzed the total magnesium concentration in these fluids. The complete analytical data are compiled in a brief review. The results of our and other relevant studies are discussed with regard to the current view on the formation and biochemical nature of PL and its interaction with CSF.