Nucleotide diphosphates activate the ATP-sensitive potassium channel in mouse skeletal muscle

✍ Scribed by Bruno Allard; Michel Lazdunski

• Publisher: Springer
• Year: 1992
• Tongue: English
• Weight: 831 KB
• Volume: 422
• Category: Article
• ISSN: 0031-6768
• DOI: 10.1007/bf00370419

✦ Synopsis

Patch-clamp techniques were used to study the effects of internal nucleotide diphosphates on the KAT e channel in mouse skeletal muscle. In inside-out patches, application of GDP (100 gM) and ADP (100 gM) reversibly increased the channel activity. In the presence of internal Mg 2+ (1 mM), low concentrations of ADP (< 300 gM) enhanced channel activity and high concentrations of ADP (> 300 gM) limited channel opening while GDP activated the channel at all concentrations tested. In the absence of internal Mg 2+, ADP decreased channel activity at all concentrations tested while GDP had no noticeable effect at submillimolar concentrations and inhibited channel activity at millimolar concentrations. GDP [flS] (100 ~tM), which behaved as a weak GDP agonist in the presence of Mg 2+ , stimulated ADPevoked activation whereas it inhibited GDP-evoked activation. The K + channel opener pinacidil was found to activate the KATP channel but only in the presence of internal GDP, ADP and GDP [flS]. The results are discussed in terms of the existence of multiple nucleotide binding sites, in charge of the regulation of the KAT e channel.