Key result
The K+ channel openers NS309 and DCEBIO concentration-dependently inhibited L-type Ca2+ channel currents in mouse urinary bladder smooth muscle cells, with IC50 values of 10.6 µM and 71.6 µM.
DCEBIO and NS309, commonly used as SK/IK channel openers, substantially block L-type Ca2+ channels, which may confound their use as pharmacological tools in excitable cells.
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May confound NS309/DCEBIO selectivity as SK/IK openers in excitable cells; leaves open in vivo relevance.
We examined effects of small and intermediate conductance Ca(2+)-activated K(+) (SK and IK) channel openers, DCEBIO (5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one) and NS309 (3-oxime-6,7-dichloro-1H-indole-2,3-dione), on L-type Ca(2+) channel current (I(Ca)) that was measured in smooth muscle cells isolated from mouse urinary bladder under whole cell voltage-clamp. The I(Ca) was concentration-dependently inhibited by DCEBIO and NS309; half inhibition was obtained at 71.6 and 10.6 muM, respectively. The specificity of NS309 to the IK channel over the Ca(2+) channel appears to be high and higher than that of DCEBIO. DCEBIO and even NS309 may, however, substantially block Ca(2+) channels when used as SK channel openers.
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Morimura et al. (2006) studied None (healthy mice). DCEBIO and NS309 vs. Control (absence of drug) was evaluated on Inhibition of L-type Ca2+ channel current (ICa) (p=<0.01). The K+ channel openers NS309 and DCEBIO concentration-dependently inhibited L-type Ca2+ channel currents in mouse urinary bladder smooth muscle cells, with IC50 values of 10.6 µM and 71.6 µM.
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