Figure 2

CO inhibition of hKv1.5 involves mitochondrial reactive oxygen species, NO and soluble guanylyl cyclase. (a) Example currents evoked in hKv1.5-expressing HEK293 cells before and during exposure to 30 μM CORM-2. Currents are examples from time-series studies (as in Figure 1) in which cells were repeatedly depolarized from −80 mV to +50 mV (100 ms duration, 0.2 Hz)). CORM-2 was applied either to untreated cells or to cells pretreated for 1 h at 37 °C with DTT (1 mM) MnTMPyP (50 μM) or MnTBAP (10 μM), as indicated. Scale bars represent 1 nA (vertical) and 50 ms (horizontal) in all cases. (b) Bar graph plotting mean (with S.E.M. bars, from number of cells indicated) % inhibition caused by CORM-2 in the absence or presence of the drugs indicated (taken from studies exemplified by current traces). ***P<0.001 (effects of CORM-2 alone when compared with controls); ***P<0.001 (comparing effects of CORM-2 alone with CORM-2 in the presence of drugs indicated). (c) As in panel (a), except cells were pretreated (1 h at 37 °C) with DPI (3 μM), allopurinol (1 μM), mitoTEMPO (10 μM) or antimycin A (3 μM), as indicated, prior to recordings. (d) Bar graph plotting mean (with S.E.M. bars) % inhibition caused by CORM-2 in the absence or presence of the drugs indicated. **P<0.01, *P<0.05, comparing the effects of CORM-2 alone or with CORM-2 in the presence of drugs indicated. Dashed line indicates the mean effect of CORM-2 alone. (e) Example currents evoked in hKv1.5-expressing HEK293 cells before and during exposure to 30 μM CORM-2. Currents are examples from time-series studies (as in Figure 1) in which cells were repeatedly depolarized from −80 to +50 mV (100 ms duration, 0.2 Hz)). CORM-2 was applied either to untreated cells or to cells pretreated with L-NAME (1 mM; 1 h, 37 °C), Rp-8-Br-cGMPS (50 μM; 1 h, 37 °C) or both agents together, as indicated. Scale bars represent 1 nA (vertical) and 50 ms (horizontal) in all cases; except the L-NAME-treated example (vertical scale bar=0.2 nA). (f) Bar graph plotting mean (with S.E.M. bars, n numbers indicated in each bar) % inhibition caused by CORM-2 in the presence of the drugs indicated (taken from studies exemplified by current traces). Mean effect of CORM-2 alone is indicated by the dashed line. ***P<0.001, significant difference from inhibition caused by CORM-2 alone