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The effect of clofilium, a K-channel blocker, on the electrogenic K secretion and the sensory discharge at the frog semicircular canal.
Brain Res. 1996 May 20; 721(1-2):174-80.BR

Abstract

Potassium transport by dark cells produces marked K-concentration differences between endo- and perilymphatic fluids in labyrinthine organs and generates the transepithelial potential. The ensuing electrochemical potential for K sustains the transduction current which regulates activity at the cytoneural junction. Clofilium, a compound which is known to block cardiac K channels and to decrease the endocochlear potential, was applied to the endolymphatic side of the isolated frog semicircular canal. The drug abolished the transepithelial potential and increased K outflux from the lumen to the dark cells (or the basolateral perilymph) with no apparent interference with active K secretion. When applied to the perilymphatic side in the intact labyrinth, clofilium reduced the rate of occurrence of miniature excitatory postsynaptic potentials (mEPSPs), both at rest and in response to mechanical stimulation (sinusoidal rotation at 0.1 Hz, 12.5 deg/s2 peak acceleration). This effect may be related to a reduced K-electrochemical unbalance and a decreased transduction current. The drug consistently reduced mEPSP size, although amplitude distributions remained log-normal and time intervals between successive mEPSPs remained exponentially distributed; this suggests a direct effect of clofilium on the postsynaptic membrane, in addition to any possible presynaptic effects. Spike discharge by the afferent fibre was almost completely abolished at rest and responses to mechanical stimulation were reduced by 85-90%. These effects cannot be accounted for by the mild reduction of mEPSP rates and confirm a direct action of clofilium on the afferent postsynaptic terminal.

Authors+Show Affiliations

Dipartimento di Biologia, Università di Ferrara, Italy.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

8793098

Citation

Rossi, M L., et al. "The Effect of Clofilium, a K-channel Blocker, On the Electrogenic K Secretion and the Sensory Discharge at the Frog Semicircular Canal." Brain Research, vol. 721, no. 1-2, 1996, pp. 174-80.
Rossi ML, Ferrary E, Martini A, et al. The effect of clofilium, a K-channel blocker, on the electrogenic K secretion and the sensory discharge at the frog semicircular canal. Brain Res. 1996;721(1-2):174-80.
Rossi, M. L., Ferrary, E., Martini, A., Martini, M., Pelucchi, B., Bernard, C., Teixeira, M., Sterkers, O., & Fesce, R. (1996). The effect of clofilium, a K-channel blocker, on the electrogenic K secretion and the sensory discharge at the frog semicircular canal. Brain Research, 721(1-2), 174-80.
Rossi ML, et al. The Effect of Clofilium, a K-channel Blocker, On the Electrogenic K Secretion and the Sensory Discharge at the Frog Semicircular Canal. Brain Res. 1996 May 20;721(1-2):174-80. PubMed PMID: 8793098.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The effect of clofilium, a K-channel blocker, on the electrogenic K secretion and the sensory discharge at the frog semicircular canal. AU - Rossi,M L, AU - Ferrary,E, AU - Martini,A, AU - Martini,M, AU - Pelucchi,B, AU - Bernard,C, AU - Teixeira,M, AU - Sterkers,O, AU - Fesce,R, PY - 1996/5/20/pubmed PY - 1996/5/20/medline PY - 1996/5/20/entrez SP - 174 EP - 80 JF - Brain research JO - Brain Res. VL - 721 IS - 1-2 N2 - Potassium transport by dark cells produces marked K-concentration differences between endo- and perilymphatic fluids in labyrinthine organs and generates the transepithelial potential. The ensuing electrochemical potential for K sustains the transduction current which regulates activity at the cytoneural junction. Clofilium, a compound which is known to block cardiac K channels and to decrease the endocochlear potential, was applied to the endolymphatic side of the isolated frog semicircular canal. The drug abolished the transepithelial potential and increased K outflux from the lumen to the dark cells (or the basolateral perilymph) with no apparent interference with active K secretion. When applied to the perilymphatic side in the intact labyrinth, clofilium reduced the rate of occurrence of miniature excitatory postsynaptic potentials (mEPSPs), both at rest and in response to mechanical stimulation (sinusoidal rotation at 0.1 Hz, 12.5 deg/s2 peak acceleration). This effect may be related to a reduced K-electrochemical unbalance and a decreased transduction current. The drug consistently reduced mEPSP size, although amplitude distributions remained log-normal and time intervals between successive mEPSPs remained exponentially distributed; this suggests a direct effect of clofilium on the postsynaptic membrane, in addition to any possible presynaptic effects. Spike discharge by the afferent fibre was almost completely abolished at rest and responses to mechanical stimulation were reduced by 85-90%. These effects cannot be accounted for by the mild reduction of mEPSP rates and confirm a direct action of clofilium on the afferent postsynaptic terminal. SN - 0006-8993 UR - https://www.unboundmedicine.com/medline/citation/8793098/The_effect_of_clofilium_a_K_channel_blocker_on_the_electrogenic_K_secretion_and_the_sensory_discharge_at_the_frog_semicircular_canal_ L2 - https://linkinghub.elsevier.com/retrieve/pii/0006-8993(96)00057-1 DB - PRIME DP - Unbound Medicine ER -