Enhancement of Ca²⁺Influx and Ciliary Beating by Membrane Hyperpolarization due to ATP-Sensitive K⁺Channel Opening in Mouse Airway Epithelial Cells

Abstract

Among the several types of cells composing the airway epithelium, the ciliary cells are responsible for one of the most important defense mechanisms of the airway epithelium: the transport of inhaled particles back up into the throat by coordinated ciliary movement. Changes in the cytoplasmic Ca 21 concentration ([Ca 21 ] i ) are the main driving force controlling the ciliary activity. In mouse ciliary cells, membrane hyperpolarization from 220 to 260 mV under whole-cell voltage-clamp induced a slow but significant [Ca 21 ] i rise in a reversible manner. This rise was completely inhibited by the removal of Ca 21 from the extracellular solution. Application of diazoxide, an ATP-dependent K 1 channel opener, dose-dependently induced a membrane hyperpolarization (EC 50 5 2.3 mM), which was prevented by the addition of 5 mM glibenclamide. An inwardly rectifying current was elicited by the application of 10 mM diazoxide and suppressed by subsequent addition of 5 mM glibenclamide. Moreover, the application of 10 mM diazoxide induced a significant [Ca 21 ] i rise and facilitated ciliary movement. Multi-cell reverse-transcription polymerase chain reaction analyses and immunocytochemical staining suggested that the subunit combination of Kir6.2/SUR2B and possibly also Kir6

Avertin®, but Not Volatile Anesthetics Addressing the Two-Pore Domain K+ Channel, TASK-1, Slows Down Cilia-Driven Particle Transport in the Mouse Trachea

“…Direct data on the link between membrane potential and CBF in airway cells are sparse and inconsistent. In isolated ciliated cells of the rabbit trachea, Ma and coworkers did not observe an impact of changes in membrane potential on CBF [36], whereas single ciliated cells of the mouse trachea, which matches more closely to the model in our study, responded to membrane hyperpolarization with enhanced Ca 2+ influx through non-voltage-gated calcium channels with subsequent rise in CBF [37]. In this latter study, membrane hyperpolarization was achieved by diazoxide, an opener of ATP-sensitive K + channels (K ATP ).…”

“…On the other hand, voltage-gated Ca 2+ channels are not ubiquitously expressed in the respiratory epithelium and restricted to certain cell types and stages of development [15, 16], and coupling of membrane potential to [Ca 2+ ] i in ciliated cells might differ from that in glomus and smooth muscle cells. A study on mouse ciliated cells even argues for an increase in CBF in response to hyperpolarizing agents due to opening of non-voltage-gated Ca 2+ channels [17]. In that case, anesthetics would even have a stimulatory effect on CBF if acting through TASK channels.…”

Caveolin-1 Facilitates the Direct Coupling between Large Conductance Ca2+-activated K+ (BKCa) and Cav1.2 Ca2+ Channels and Their Clustering to Regulate Membrane Excitability in Vascular Myocytes

“…Cells were immunostained as described previously (34). Dissociated cells settled on glass-bottom dishes (Matsunami Glass Industry, Osaka, Japan) were labeled with 1:100 diluted antibodies for 12 h at 4°C after fixation and permeabilization.…”

Orai1–Orai2 complex is involved in store-operated calcium entry in chondrocyte cell lines

“…Resulting images were analyzed by a LAS-1000 device (Fujifilm, Tokyo, Japan). Cells were immunostained as described previously [26]. Orai1 and Orai2 in OUMS-27 cells were labeled with monoclonal antiOrai1 antibody (sc-377281, Santa Cruz Biotechnology, Inc., Dallas, TX, USA) and polyclonal anti-Orai2 antibody, respectively.…”