| 저자(한글) |
Bae, Hyemi,Lee, Donghee,Kim, Young-Won,Choi, Jeongyoon,Lee, Hong Jun,Kim, Sang-Wook,Kim, Taeho,Noh, Yun-Hee,Ko, Jae-Hong,Bang, Hyoweon,Lim, Inja |
| 초록 |
Human cardiac fibroblasts (HCFs) have various voltage-dependent $K^+$ channels (VDKCs) that can induce apoptosis. Hydrogen peroxide ( $H_2O_2$ ) modulates VDKCs and induces oxidative stress, which is the main contributor to cardiac injury and cardiac remodeling. We investigated whether $H_2O_2$ could modulate VDKCs in HCFs and induce cell injury through this process. In whole-cell mode patch-clamp recordings, application of $H_2O_2$ stimulated $Ca^{2+}-activated$ $K^+$ ( $K_{Ca}$ ) currents but not delayed rectifier $K^+$ or transient outward $K^+$ currents, all of which are VDKCs. $H_2O_2-stimulated$ $K_{Ca}$ currents were blocked by iberiotoxin (IbTX, a large conductance $K_{Ca}$ blocker). The $H_2O_2-stimulating$ effect on large-conductance $K_{Ca}$ ( $BK_{Ca}$ ) currents was also blocked by KT5823 (a protein kinase G inhibitor) and 1 H-[1, 2, 4] oxadiazolo-[4, 3-a] quinoxalin-1-one (ODQ, a soluble guanylate cyclase inhibitor). In addition, 8-bromo-cyclic guanosine 3', 5'-monophosphate (8-Br-cGMP) stimulated $BK_{Ca}$ currents. In contrast, KT5720 and H-89 (protein kinase A inhibitors) did not block the $H_2O_2-stimulating$ effect on $BK_{Ca}$ currents. Using RT-PCR and western blot analysis, three subtypes of $K_{Ca}$ channels were detected in HCFs: $BK_{Ca}$ channels, small-conductance $K_{Ca}$ ( $SK_{Ca}$ ) channels, and intermediate-conductance $K_{Ca}$ ( $IK_{Ca}$ ) channels. In the annexin V/propidium iodide assay, apoptotic changes in HCFs increased in response to $H_2O_2$ , but IbTX decreased $H_2O_2$ -induced apoptosis. These data suggest that among the VDKCs of HCFs, $H_2O_2$ only enhances $BK_{Ca}$ currents through the protein kinase G pathway but not the protein kinase A pathway, and is involved in cell injury through $BK_{Ca}$ channels. |
