Involvement of Cl- transport in forskolin-induced elevation of endocochlear potential.
To determine the possible involvement of Cl- transport in the forskolin-induced endocochlear potential (EP) elevation, the effect of forskolin on the EP was examined in Cl(-)-free artificial perilymph (aPL) as well as in the presence of Cl- channel blockers. The perfusion of scala vestibuli (SV) with forskolin (200 microM) dissolved in Cl(-)-free aPL failed to produce an EP elevation, while SV perfusion of forskolin dissolved in normal aPL elevated the EP. The application of DPC and IAA-94 (blockers of cAMP-activated Cl- channel) into SV completely suppressed the forskolin-induced EP elevation, while niflumic acid (a Ca(2+)-activated Cl- channel blocker) failed to do so. IAA-94 applied into scala tympani (ST) did not suppress this EP elevation. The results suggest that adenylate cyclase may modulate the EP by changing Cl- transport between SV and scala media (SM) across Reissner's membrane.
Kitano
I
I
Department of Otolaryngology, Nara Medical University, Japan.
Doi
K
K
Mori
N
N
Matsunaga
T
T
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D018118:Chloride Channels / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism*; D003051:Cochlea / Q000187:drug effects* / Q000378:metabolism; D003053:Cochlear Duct / Q000187:drug effects* / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology*; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D006016:Glycolates / Q000494:pharmacology; D006168:Guinea Pigs; D010498:Perilymph / Q000187:drug effects / Q000378:metabolism; D062367:ortho-Aminobenzoates / Q000494:pharmacology
D018118:Chloride Channels; D002712:Chlorides; D006016:Glycolates; D062367:ortho-Aminobenzoates; D005576:Colforsin; C015765:MK 473; C001209:fenamic acid; D000262:Adenylyl Cyclases