Supporting sensory transduction: cochlear fluid homeostasis and the endocochlear potential.
The exquisite sensitivity of the cochlea, which mediates the transduction of sound waves into nerve impulses, depends on the endocochlear potential and requires a highly specialized environment that enables and sustains sensory function. Disturbance of cochlear homeostasis is the cause of many forms of hearing loss including the most frequently occurring syndromic and non-syndromic forms of hereditary hearing loss, Pendred syndrome and Cx26-related deafness. The occurrence of these and other monogenetic disorders illustrates that cochlear fluid homeostasis and the generation of the endocochlear potential are poorly secured by functional redundancy. This review summarizes the most prominent aspects of cochlear fluid homeostasis. It covers cochlear fluid composition, the generation of the endocochlear potential, K(+) secretion and cycling and its regulation, the role of gap junctions, mechanisms of acid-base homeostasis, and Ca(2+) transport.
Wangemann
Philine
P
Anatomy & Physiology Department, 205 Coles Hall, Kansas State University, Manhattan, 66506, USA. wange@vet.k-state.edu
D000136:Acid-Base Equilibrium / Q000502:physiology; D000818:Animals; D003051:Cochlea / Q000166:cytology / Q000294:innervation / Q000502:physiology*; D000072259:Connexin 26; D017630:Connexins; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D045604:Extracellular Fluid / Q000502:physiology*; D017629:Gap Junctions / Q000502:physiology; D034381:Hearing Loss / Q000503:physiopathology; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D009475:Neurons, Afferent / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology
D017630:Connexins; C000607042:GJB2 protein, human; D015221:Potassium Channels; D000072259:Connexin 26; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium