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

[摘要] 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 cr-subunits expressed in Xenopus oocytes and native cGMP-gated channels from Xenopus rod outer segments. When co-applied with 100 mu M 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. (C) 1997 Elsevier Science Ireland Ltd.

[发布日期] 1997-09-12

[关键词] H-8;cGMP-dependent protein kinase inhibitor;cloned rat rod cGMP-gated cationic channel alpha-subunit;Xenopus oocytes expression;Xenopus retinal rod outer segment;patch clamp recordings