Properties of ion channels in rabbit mesenchymal stem cells from bone marrow

The present study was designed to investigate properties of ion channels in undifferentiated rabbit mesenchymal stem cells (MSCs) from bone marrow using whole-cell patch-clamp and RT-PCR techniques. It was found that three types of outward currents were present in rabbit MSCs, including an inward rectifier K+ current (IKir), a noise-like Ca2+-activated K+ current (IKCa) co-present with delayed rectifier K+ current (IKDR). IKir was inhibited by Ba2+, while IKCa was inhibited by paxilline (a blocker of big conductance IKCa channels) and clotrimazole (an inhibitor of intermediate conductance IKCa channels). IKDR exhibited a slow inactivation, “U-shaped” voltage-dependent inactivation, and slow recovery from inactivation, and the current was inhibited by tetraethylammonium or 4-aminopyridine. RT-PCR revealed the molecular identities for the functional ionic currents, including Kir1.1 (possibly responsible for IKir), KCa1.1 and KCa3.1 (possibly responsible for IKCa), and Kv1.2, Kv2.1, and Kv2.2 (possibly responsible for IKDR). These results demonstrate for the first time that three types of functional ion channel currents (i.e., IKir, IKCa, and IKDR) are present in rabbit MSCs from bone marrow.