Glimepiride block of cloned β‐cell, cardiac and smooth muscle KATP channels
Open Access
- 1 May 2001
- journal article
- Published by Wiley in British Journal of Pharmacology
- Vol. 133 (1) , 193-199
- https://doi.org/10.1038/sj.bjp.0704062
Abstract
We examined the effect of the sulphonylurea glimepiride on three types of recombinant ATP‐sensitive potassium (KATP) channels. KATP channels share a common pore‐forming subunit, Kir6.2, which associates with different sulphonylurea receptor isoforms (SUR1 in β‐cells, SUR2A in heart and SUR2B in smooth muscle). Kir6.2 was coexpressed with SUR1, SUR2A or SUR2B in Xenopus oocytes and macroscopic KATP currents were recorded from giant inside‐out membrane patches. Glimepiride was added to the intracellular membrane surface. Glimepiride inhibited Kir6.2/SUR currents by interaction with two sites: a low‐affinity site on Kir6.2 (IC50=∼400 μM) and a high‐affinity site on SUR (IC50=3.0 nM for SUR1, 5.4 nM for SUR2A and 7.3 nM for SUR2B). The potency of glimepiride at the high‐affinity site is close to that observed for glibenclamide (4 nM for SUR1, 27 nM for SUR2A), which has a similar structure. Glimepiride inhibition of Kir6.2/SUR2A and Kir6.2/SUR2B currents, but not Kir6.2/SUR1 currents, reversed rapidly. Our results indicate that glimepiride is a high‐affinity sulphonylurea that does not select between the β‐cell, cardiac and smooth muscle types of recombinant KATP channel, when measured in inside‐out patches. High‐affinity inhibition is mediated by interaction of the drug with the sulphonylurea receptor subunit of the channel. British Journal of Pharmacology (2001) 133, 193–199; doi:10.1038/sj.bjp.0704062Keywords
This publication has 39 references indexed in Scilit:
- ATP-sensitive K + channels and insulin secretion: their role in health and diseaseDiabetologia, 1999
- PIP 2 and PIP as Determinants for ATP Inhibition of K ATP ChannelsScience, 1998
- Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33)The Lancet, 1998
- Truncation of Kir6.2 produces ATP-sensitive K+ channels in the absence of the sulphonylurea receptorNature, 1997
- Cardiovascular Effects of Conventional Sulfonylureas and GlimepirideHormone and Metabolic Research, 1996
- A Family of Sulfonylurea Receptors Determines the Pharmacological Properties of ATP-Sensitive K+ ChannelsPublished by Elsevier ,1996
- Cloning and functional expression of the cDNA encoding a novel ATP‐sensitive potassium channel subunit expressed in pancreatic β‐cells, brain, heart and skeletal muscleFEBS Letters, 1995
- Differential interaction of glimepiride and glibenclamide with the β-cell sulfonylurea receptor II. Photoaffinity labeling of a 65 kDa protein by [3H]glimepirideBiochimica et Biophysica Acta (BBA) - Biomembranes, 1994
- Differential interaction of glimepiride and glibenclamide with the β-cell sulfonylurea receptor I. Binding characteristicsBiochimica et Biophysica Acta (BBA) - Biomembranes, 1994
- Cytosolic ADP enhances the sensitivity to tolbutamide of ATP‐dependent K+ channels from pancreatic B‐cellsFEBS Letters, 1988