Research About Ion Channel Electrophysiological Characteristics Of Cardiac C-kit~+ Cells From Adult Mouse And The Effect Of Trimethyl-apigenin On Kv1.5 Channel

PartⅠIon channel electrophysiological characteristics of cardiac stem cells from adult mouseCardiac c-kit+ cells are generally believed to be the major population of stem/progenitor cells in the heart and can be used as a cell source for cardiomyoplasty; however, the cellular electrophysiological properties are not understood in this type of cells. The present study was to investigate functional ion channels in undifferentiated mouse cardiac c-kit+ cells using approaches of whole-cell patch voltage clamp, RT-PCR, and cell proliferation assay. It was found that three types of ionic currents were present in mouse cardiac c-kit+ cells, including a delayed rectifier K+ current (IKDR) inhibited by 4-aminopyridine (4-AP), an inward rectifier K+ current (IKir) decreased by Ba2+, and a volume-sensitive chloride current (ICl.vol) inhibited by 5-nitro-1-(3-phenylpropylamino) benzoic acid (NPPB). RT-PCR revealed that the corresponding ion channel genes, Kv1.1, Kv1.2, and Kv1.6 (for IKDR), Kir.1.1, Kir2.1 and Kir2.2 (likely responsible for IKir), and Clcn3 (for ICl.vol) were significant in mouse cardiac c-kit+ cells. The results demonstrate that three types of functional ion channel currents (i.e., IKDR, IKir, and ICl.vol) are present in mouse cardiac c-kit+ cells.PartⅡEffects of TMA on the KV1.5 channel in HEK293 cellThe effects of TMA on the kv1.5 channel in HEK293 cell were investigated. 10μmol·L-1 verapamil decreased ultra rapid delayed K+ current by 87±5 %, and this effects were partially reversed by washout. 1, 3μmol·L-1 TMA significant suppress IKur by 67±2% , 96±1%, respectively(n=5,P<0.01). The IC50 of TMA effect on IKur is 0.64μmol·L-1.