Elsevier

Neuroscience Letters

Volume 233, Issue 1, 12 September 1997, Pages 37-40
Neuroscience Letters

Direct blockade of both cloned rat rod photoreceptor cyclic nucleotide-gated non-selective cation (CNG) channel α-subunit and native CNG channels from Xenopus rod outer segments by H-8, a non-specific cyclic nucleotide-dependent protein kinase inhibitor

https://doi.org/10.1016/S0304-3940(97)00622-8Get rights and content
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Abstract

Using excised inside-out patch techniques, a non-specific cyclic nucleotide-dependent protein kinase inhibitor, H-8 (N-2-(methylamino)ethyl-5-isoquinolinesulfonamide), has been shown to suppress directly the activities of both rat rod photoreceptor cyclic GMP-gated channel α-subunits expressed in Xenopus oocytes and native cGMP-gated channels from Xenopus rod outer segments. When co-applied with 100 μM cGMP on the cytoplasmic side of the patches, current suppression by H-8 increased with membrane depolarization. Blockade by H-8 was not relieved by supersaturating concentrations of cGMP (1 mM). In addition, blockade by H-8 showed significant inhibition of channel activity at negative holding potentials when acting from the extracellular side of the channel. The results were consistent with the conclusion that H-8 can act as an open channel blocker from either side of the channel. Even though H-8 is a much more effective kinase inhibitor, it is frequently used at concentrations that cause inhibition of cGMP-gated channels and this effect needs to be taken into account when evaluating results obtained with this compound.

Keywords

H-8
cGMP-dependent protein kinase inhibitor
Cloned rat rod cGMP-gated cationic channel α-subunit
Xenopus oocytes expression
Xenopus retinal rod outer segment
Patch clamp recordings

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