title: The fast activating potassium current, I(K,f), in guinea-pig inner hair cells is regulated by protein kinase A.
abstract: The mammalian inner hair cell (IHC) responds to displacements produced in the cochlea by sound by releasing neurotransmitter from its basal pole. A basolateral fast activating potassium current, called I(K,f), allows IHCs to act as sensory cells at high frequencies by shortening the membrane time constant. This current is co-expressed with a slower activating current, I(K,s). We have studied the intracellular regulation of IHC currents using the whole-cell patch clamp technique in conjunction with agents that influence the function of protein kinase A (PKA). Bath applied 8-Bromo-cAMP, an activator of PKA, increased the amplitude of outwardly rectifying currents and shortened the exponential time constant of activation. Following blockade of I(K,s) by intracellular 4-AP, I(K,f) could be reduced in amplitude by H-89, an inhibitor of PKA. Our results suggest that PKA regulates I(K,f) and so shapes the frequency response of IHCs.
authors.affiliation: Department of Physiology, University College London, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Jagger
authors.forename: J F
authors.initials: JF
authors.lastname: Ashmore
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006168:Guinea Pigs; D006199:Hair Cells, Auditory, Inner / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D013449:Sulfonamides
chemical_list: D004791:Enzyme Inhibitors; D007546:Isoquinolines; D015221:Potassium Channels; D013449:Sulfonamides; D015124:8-Bromo Cyclic Adenosine Monophosphate; D004533:Egtazic Acid; D015761:4-Aminopyridine; D017868:Cyclic AMP-Dependent Protein Kinases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide