The effects of nucleotides and potassium channel openers on the SUR2A/Kir6.2 complex K + channel expressed in a mammalian cell line, HEK293T cells

Okuyama, Yuji; Yamada, Mitsuhiko; Kondo, Chikako; Satoh, Eiichi; Isomoto, Shojiro; Shindo, Takashi; Horio, Yoshiyuki; Kitakaze, Masafumi; Hori, Masatsugu; Kurachi, Yoshihisa

doi:10.1007/s004240050559

Cited by 79 publications

(54 citation statements)

References 36 publications

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“…Therefore, the pancreatic channel was also assayed in the inside-out configuration. To account for the higher inhibitory potency of MgATP in this configuration, MgATP was reduced to 0.03 mmol/l and MgUDP (0.3 mmol/l) was added to activate SUR without inhibiting Kir6.2 [37]. The inhibition kinetics was now approximately seven-fold faster (not illustrated), allowing inhibition curves to be measured (Fig.…”

Section: Inhibition Of K Atp Channel Subtypesmentioning

confidence: 99%

Selectivity of repaglinide and glibenclamide for the pancreatic over the cardiovascular KATP channels

et al. 2006

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Aims/hypothesis Sulfonylureas and glinides close beta cell ATP-sensitive K + (K ATP ) channels to increase insulin release; the concomitant closure of cardiovascular K ATP channels, however, leads to complications in patients with cardiac ischaemia. The insulinotrope repaglinide is successful in therapy, but has been reported to inhibit the recombinant K ATP channels of beta cells, cardiocytes and non-vascular smooth muscle cells with similar potencies, suggesting that the (patho-)physiological role of the cardiovascular K ATP channels may be overstated. We therefore re-examined repaglinide's potency at and affinity for the recombinant pancreatic, myocardial and vascular K ATP channels in comparison with glibenclamide. Results Repaglinide and glibenclamide, respectively, were ≥30 and ≥1,000 times more potent in closing the pancreatic than the cardiovascular channels and they did not lead to complete inhibition of the myocardial channel. Binding assays showed that the selectivity of glibenclamide was essentially based on high affinity for the pancreatic SUR, whereas binding of repaglinide to the SUR subtypes was rather non-selective. After coexpression with Kir6.x to form the assembled channels, however, the affinity of the pancreatic channel for repaglinide was increased 130-fold, an effect much larger than with the cardiovascular channels. This selective effect of coexpression depended on the piperidino substituent in repaglinide. Conclusions/interpretation Repaglinide and glibenclamide show higher potency and efficacy in inhibiting the pancreatic than the cardiovascular K ATP channels, thus supporting their clinical use.

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Section: Inhibition Of K Atp Channel Subtypesmentioning

confidence: 99%

Selectivity of repaglinide and glibenclamide for the pancreatic over the cardiovascular KATP channels

et al. 2006

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“…E-mail: m.schwanstecher@tu-bs.de. 1 The abbreviations used are: KCO, potassium channel opener; K ATP , ATP-sensitive K ϩ channel; KCO I and KCO II, potassium channel opener binding regions; K IR , inwardly rectifying K ϩ channel; NBF, nucleotide binding fold; SU, sulfonylurea; SUBR, sulfonylurea binding region; SUR, sulfonylurea receptor; TMD, transmembrane domain; TMDI or TMDII, first (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) or second (12)(13)(14)(15)(16)(17) set of transmembrane domains (see Fig. 1, A or F); DMEM, Dulbecco's modified Eagle's medium.…”

Section: Materials and Solutions-[mentioning

confidence: 99%

“…SUR1/ K IR 6.2 have been proposed to reconstitute the neuronal/pancreatic ␤-cell (5), SUR2A/K IR 6.2, the cardiac (6,13,14), and SUR2B/K IR 6.1 (or K IR 6.2), the vascular smooth muscle-type K ATP channels (8,11,15,16).…”

mentioning

confidence: 99%

Identification of the Potassium Channel Opener Site on Sulfonylurea Receptors

Uhde¹,

Toman²,

Gross

et al. 1999

Journal of Biological Chemistry

114

123

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“…17 Although both Kir6.1 and Kir6.2 mRNAs are abundantly expressed in the heart, 18 the expressed K ATP channels composed of Kir6.2 and SUR2A reproduced the major properties of the native cardiac K ATP channel well in terms of nucleotide regulation and pharmacology. 19 It was also reported that the gene expression of Kir6.1 and of Kir6.2 is differently regulated in cardiac tissue. 20,21 In chick heart, ATP depletion or Kir6.2 has been thought to be composed of K ATP channels with SUR2B in smooth muscles such as murine colon and guinea-pig urinary bladder.…”

Section: Discussionmentioning

confidence: 98%

Molecular basis and characteristics of KATP channel in human corporal smooth muscle cells

et al. 2003

Int J Impot Res

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Relaxation of the corpus cavernosum smooth muscle is an absolute prerequisite for penile erection. Potassium channels play a role in the physiologic regulation of corporal smooth muscle tone. In spite of the physiological importance of K ATP channel in the modulation of corporal smooth muscle tone, there is a shortage of information available about the K ATP channel subtype(s) present in the corporal smooth muscle. The purpose of this study was to investigate the subunit type of K ATP channel, that is, the combinations of the Kir subunit and the SUR subunit in the human corporal smooth muscle and determine whether the electrophysiological kinetics and pharmacological properties of K ATP channels meet the subunit characteristics of the ion channel. We used cultured human corporal smooth muscle cells. To determine the presence of Kir and SURs subunits, RT-PCR was performed using Kir6.1, Kir6.2, SUR1, SUR2A, and SUR2B gene-specific primers. For electrophysiological recordings, the whole-cell, inside-out, and cell-attached configurations of the patch-clamp technique were used. We observed transcripts for Kir6.1, Kir6.2, and SUR2B in mRNA isolated from smooth muscle cells of cultured human corpus carvernosum. We recorded the unitary K ATP channel under the condition of intracellular and extracellular 140 mM [K + ], and the slope conductance of the channel was 42.0 7 2.6 pS which is an intermediate conductance between that of either Kir6.1 or Kir6.2. The pinacidil (10 lM) increased the magnitude of the outward K + current (214.6 7 89.2%, n ¼ 12, Po0.05), which was blocked by the subsequent addition of the specific K ATP channel subtype selective blocker, glibenclamide (10 lM). The SIN-1(200 lM) induced increases in whole-cell outward K + currents (126.0 7 1.4%, n ¼ 4). The increased currents by SIN-1 were inhibited by glibenclamide (10 lM). We are the first to show that K ATP channel in human corporal smooth muscle is composed of Kir6.1-Kir6.2 construct expressed with SUR2B by RT-PCR. These findings, taken together with the electrophysiological results, suggest that K ATP channel in corporal smooth muscle cells is composed of heteromultimers of Kir6.1 and Kir6.2 with the ratio of 3 : 1 or 4 : 0 and SUR2B.

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The effects of nucleotides and potassium channel openers on the SUR2A/Kir6.2 complex K + channel expressed in a mammalian cell line, HEK293T cells

Cited by 79 publications

References 36 publications

Selectivity of repaglinide and glibenclamide for the pancreatic over the cardiovascular KATP channels

Selectivity of repaglinide and glibenclamide for the pancreatic over the cardiovascular KATP channels

Identification of the Potassium Channel Opener Site on Sulfonylurea Receptors

Molecular basis and characteristics of KATP channel in human corporal smooth muscle cells

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