Potentiation of nicotinic currents by bradykinin in the paratracheal ganglia neurons of rats

Abstract

The effects of bradykinin on nicotine-induced responses were investigated in neurons dissociated from rat paratracheal ganglia using the nystatin-perforated patch-clamp recording technique. When bradykinin (10 − 9 to 10 − 8 M) was pretreated and then simultaneously applied with 10 − 5 M nicotine, bradykinin potentiated the nicotine-induced currents. The potentiation was mimicked by [Hyp 3]-bradykinin and inhibited by HOE-140, pertussis toxin, neomycin and U-73122, but not U-73433. These results suggest that bradykinin potentiates nicotinic currents via bradykinin B 2 receptor, pertussis toxin-sensitive G-protein and phospholipase C. Since bradykinin inhibits the M-current via bradykinin B 2 receptor and pertussis toxin-insensitive G-protein [Mochidome, T., Ishibashi, H., Takahama, K., 2001. Bradykinin activates airway parasympathetic ganglion neurons by inhibiting M-currents. Neuroscience 105, 785–791.], it seemed that bradykinin B 2 receptor activated two distinct signal transduction pathways in the paratracheal ganglia neurons. This effect of bradykinin might cause enhanced synaptic transmission in paratracheal ganglia neurons and contribute to the aggravation of pathological conditions of the lower airway via enhanced acetylcholine release from the postganglionic nerve terminals.