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Effects of I(Ks) channel inhibitors in insulin-secreting INS-1 cells.

Authors: Ullrich, S  Su, J  Ranta, F  Wittekindt, OH  Ris, F  Rosler, M  Gerlach, U  Heitzmann, D  Warth, R  Lang, F 
Citation: Ullrich S, etal., Pflugers Arch. 2005 Dec;451(3):428-36. Epub 2005 Aug 30.
Pubmed: (View Article at PubMed) PMID:16133261
DOI: Full-text: DOI:10.1007/s00424-005-1479-2

Potassium channels regulate insulin secretion. The closure of K(ATP) channels leads to membrane depolarisation, which triggers Ca(2+) influx and stimulates insulin secretion. The subsequent activation of K(+) channels terminates secretion. We examined whether KCNQ1 channels are expressed in pancreatic beta-cells and analysed their functional role. Using RT/PCR cellular mRNA of KCNQ1 but not of KCNE1 channels was detected in INS-1 cells. Effects of two sulfonamide analogues, 293B and HMR1556, inhibitors of KCNQ1 channels, were examined on voltage-activated outwardly rectifying K(+) currents using the patch-clamp method. It was found that 293B inhibited 60% of whole-cell outward currents induced by voltage pulses from -70 to +50 mV with a concentration for half-maximal inhibition (IC(50)) of 37 microM. The other sulfonamide analogue HMR1556 inhibited 48% of the outward current with an IC(50) of 7 microM. The chromanol 293B had no effect on tolbutamide-sensitive K(ATP) channels. Action potentials induced by current injections were broadened and after-repolarisation was attenuated by 293B. Insulin secretion in the presence but not in the absence of tolbutamide was significantly increased by 293B. These results suggest that 293B- and HMR1556-sensitive channels, probably in concert with other voltage-activated K(+) channels, influence action potential duration and frequency and thus insulin secretion.


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CRRD Object Information
CRRD ID: 1581603
Created: 2006-10-07
Species: All species
Last Modified: 2006-10-07
Status: ACTIVE


RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.