2P045 Noradrenaline-induced current in rat airway ganglion neurons

The noradrenaline (NA)-induced cation current was investigated in the neurons acutely isolated from rat airway parasympathetic ganglia using nystatin-perforated patch recording configuration. NA induced a large inward current in a divalent cation free solution at a holding potential of -60mV. The NA-induced current was inhibited by extracellular Ca2+ or Mg2+. Cirazoline mimicked the NA response, and prazosin and WB4101 inhibited the NA-induced current, suggesting the contribution of an α1-adrenoceptor. The NA-induced current was inhibited by U73122, a phospholipase C (PLC) inhibitor. A membrane permeable IP3 receptor blocker, XeC also blocked the NA-induced current. Furthermore, pretreatment of thapsigargin and BAPTA-AM could inhibit the NA response while KN-62, PMA and staurosporine had no effect. These results suggest that NA activates the extracellular Ca2+- and Mg2+-sensitive cation channels via α1-adrenoceptors in the neurons freshly isolated from the rat airway ganglia. This activation mechanism involves the phosphoinositide breakdown, release of Ca2+ from intracellular Ca2+ store and calmodulin. The present findings suggest the physiological importance of sympathetic/parasympathetic interplay in the airway.