Abstract
It is well established that extracellular adenine nucleosides and nucleotides (adenosine, ATP and ADP) can influence cellular function in a range of tissues1. Interacting through specific receptors, termed purinoceptors, these compounds are known to act as neurotransmitters, neuromodulators, and humoral and trophic factors. Purinoceptors are classified into two main classes: P1 purinoceptors (subtypes A1, A2a, A2b and A3) which are preferentially responsive to adenosine and P2 purinoceptors (subtypes P2x and P2y) which are responsive to purine nucleotides (ATP, ADP, AMP)1. Over the past five years considerable evidence has emerged for a complex signalling role for extracellular purines in the inner ear2. Purinoceptors (P2x and P2y) have been identified in neural, sensory and secretory structures of the inner ear. Functional studies have shown a significant effect of extracellular ATP on inner ear function3, 4 and more recent studies have identified putative stores of ATP in secretory tissues. In addition, there is evidence for endogenous release of ATP into the fluids5 and for the presence of ectonucleotidases in cochlear tissues6. Our studies have been directed at identifying the functional role of extracellular ATP in the cochlea, that part of the inner ear which transduces sound into neural activity in the eighth cranial nerve (the auditory nerve). In this paper we summarise our current evidence on the nature and distribution of P2 purinoceptors, the storage and release of ATP and the extracellular hydrolysis of ATP in the cochlea. On the basis of this evidence we speculate on the significance of a neuromodulatory and humoral role for extracellular ATP in cochlear function and hence our sense of hearing.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
G. Burnstoek, 1996, Introduction — purinergic transmission, Semin. Neurosci. 8:171–174
P. Thorne and G. Housley, 1996, Purinergic signalling in sensory systems, Semin. Neurosci. 8:233–246
S.G. Kujawa, C. Erostegui, M. Fallon, J. Crist and R.P. Bobbin, 1994, Effects of adenosine 5′-triphosphate and related agonists on cochlear function, Hear. Res. 76:87–100
D.J.B. Munoz, P.R. Thorne, G.D. Housley, T.E. Billett and J.M. Battersby, 1995a, Extracellular adenosine 5′-triphosphate (ATP) in the endolymphatic compartment influences cochlear function, Hear. Res. 90:106–118
D.J.B. Muñoz, P.R. Thome, G.D. Housley and T.E. Billett, 1995b, Adenosine 5′-triphosphate (ATP) concentrations in the endolymph and perilymph of the guinea pig cochlea. Hear. Res. 90:119–125
S.M. Vlajkovic, P.R. Thome, D.J.B. Muñoz and G.D. Housley, 1996, Ectonucleotidase activity in the perilymphatic compartment of the guinea-pig cochlea, Hear. Res. 99:31–37.
J. Pickles, 1988, An introduction to the physiology of hearing, Academic Press, London
J.F. Ashmore, 1994, The G.L. Brown Prize Lecture. The cellular machinery of the cochlea, Exp. Physiol. 79:113–34
B.G. Mockett, X. Bo, G.D. Housley, P.R. Thome and G. Burnstock, 1995, Autoradiographic labelling of P2 purinoceptors in the guinea-pig cochlea, Hear. Res. 84:177–193
G.D. Housley, D. Greenwood and J.F. Ashmore, 1992, Localization of cholinergic and purinergic receptors on outer hair cells isolated from the guinea-pig cochlea, Proc. R. Soc. Lond. Biol. Sci. 249:265–273
G.D. Housley, D. Greenwood, B.G. Mockett, D.J.B. Muñoz and P.R. Thome, 1993, Differential actions of ATP-activated conductances in outer and inner hair cells isolated from the guinea-pig organ of Corti: A humoral purinergic influence on cochlear function, in: Biophysics of Hair Cell Sensory Systems, (H. Duifhuis, J.W. Horst, P. van Dijk and S. M. van Netten, eds.), pp. 116–123, World Scientific, Singapore.
G.D. Housley, D. Greenwood, R. Kanjhan, N.P. Raybould, P.R. Thorne, D. Christie, T. Bennett, L. Lin and A.F. Ryan, 1996, Differential expression of P2x isoforms in the cochlea. Drug Dev. Res. 37(3): 171
B.G. Mockett, G.D. Housley and P.R. Thome, 1994, Fluorescence imaging of extracellular purinergic receptor sites and putative ecto-ATPase sites on isolated cochlear hair cells, J. Neurosci. 14:6992–7007
R. Kanjhan, G.D. Housley, P.R. Thome, D. Christie, L. Lin and A.F. Ryan, 1996, Immunohistochemical detection of the P2Ă—2 purinoceptor subunit in mammalian CNS. Drug Dev. Res. 37(3): 157
P.N. White, P.R. Thome, G.D. Housley, B.M. Mockett, T.E. Billett and G. Bumstock, 1995, Quinacrine staining of marginal cells in the stria vascularis of the guinea-pig cochlea: a possible source of extracellular ATP? Hear Res. 90:97–105
S.M. Vlajkovic, P.R. Thome, D.J.B. Muñoz and G.D. Housley, 1996, Ectonucelotidases in the guinea-pig cochlea: In vivo and in vitro biochemical studies. This volume pp. 15–19.
D. Muñoz, P. Thorne and C. McFie, 1996, Modulation of cochlear blood flow by extracellular purines, Drug Develop. Res. 37(3): 183
J. F. Ashmore and H. Ohmori, 1990, Control of intracellular calcium by ATP in isolated outer hair cells of the guinea-pig cochlea, J. Physiol (Lond). 360:397–422
D. Dulon, P. Mollard and J.-M. Aran, 1991, Extracellular ATP elevates cytosolic Ca2+ in cochlear inner hair cells., NeuroReport 2:69–72
J.F. Ashmore, G.D. Housley and P.J. Kolston, 1992, Two control systems for the outer hair cell motor., Adv.Biosci. 83:19–25
D. Dulon, R. Moataz and P. Mollard, 1993, Characterization of Ca2+ signals generated by extracellular nucleotides in supporting cells of the organ of Corti, Cell Cal. 14:245–254
R. Nilles, L. Jarlebark, H.P. Zenner and E. Heilbronn, 1994, ATP-induced cytoplasmic [Ca2+] increases in isolated cochlear outer hair cells. Involved receptor and channel mechanisms, Hear Res. 73:21–34
M. Sugasawa, C. Erostegui, C. Blanchet and D. Dulon, 1996, Dual control by extracellular ATP of receptor-operated cation channels and receptor-mediated calcium mobilization in inner hair cells of the guinea-pig cochlea, J. Physiol. 491.3:707–718
D. Dulon, P. Mollard and J.M. Aran, 1991, Extracellular ATP elevates cytosolic Ca2+ in cochlear inner hair cells, Neuroreport 2:69–72
M. Suzuki, K. Ikeda, Y. Saito, A. Nishiyama and T. Takasaka, 1995, ATP-induced increase in intracellular Ca2+ concentration in the cultured marginal cell of the stria vascularis of guinea-pigs., Hear. Res. 86:68–76
J. Liu, K. Kozakura and D.C. Marcus, 1995, Evidence for purinergic receptors in vestibular dark cell and strial marginal cell epithelia of the gerbil, Auditory Neuroscience 1: 331–340
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1997 Springer Science+Business Media New York
About this chapter
Cite this chapter
Thorne, P.R., Housley, G.D., Vlajkovic, S.M., Muñoz, D.J.B. (1997). Ectonucleotidases and Purinoceptors in the Cochlea and Their Putative Role in Hearing. In: Plesner, L., Kirley, T.L., Knowles, A.F. (eds) Ecto-ATPases. Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-5955-9_30
Download citation
DOI: https://doi.org/10.1007/978-1-4615-5955-9_30
Publisher Name: Springer, Boston, MA
Print ISBN: 978-1-4613-7729-0
Online ISBN: 978-1-4615-5955-9
eBook Packages: Springer Book Archive