Modulation of BK channel activities by calcium-sensing receptor in rat bronchopulmonary sensory neurons.

This study was carried out to investigate the expression of large-conductance Ca(2+)-activated potassium (BK) channels and to explore the possible modulation of BK channel activities by calcium-sensing receptors (CaSR) in rat bronchopulmonary sensory neurons. The expression of BK channels was demonstrated by immunohistochemistry and RT-PCR. Results from whole-cell patch-clamp recordings demonstrated that activation of CaSR with its agonist spermine or NPS R-568 showed a dual regulating effect on BK channel activities: it potentiated BK currents in cells exhibiting low baseline BK activity while slightly inhibited BK currents in cells with high baseline BK activity. Blocking CaSR with its antagonist NPS 2143 significantly inhibited BK currents. Our results further showed that the modulation of BK currents by CaSR activation or blockade was completely abolished when the intracellular Ca(2+) was chelated by BAPTA-AM. In summary, our data suggest that CaSR plays an integrative role in bronchopulmonary afferent signaling, at least partially through the regulation of BK channel activities.