Dunn P M, Coote P R, Wood J N, Burgess G M, Rang H P
Sandoz Institute for Medical Research, London, U.K.
Brain Res. 1991 Apr 5;545(1-2):80-6. doi: 10.1016/0006-8993(91)91272-3.
Application of bradykinin (Bk) to neuroblastoma x dorsal root ganglion (DRG) neurone hybrid cells (ND7/23) evoked an inward (depolarizing) current associated with an increase in membrane conductance. This response was antagonized by D-Arg0,Hyp3,Thi5,8,D-Phe7-Bk, but was not mimicked by des-Arg9-Bk, indicating the involvement of B2-receptors. The response was unaltered by replacement of extracellular Na+ by N-methylglucamine. Replacement of extracellular Cl by gluconate shifted the estimate reversal potential to a more positive value, while the use of potassium acetate filled recording electrodes shifted the reversal potential to a more negative value, and reduced the response amplitude, indicating the importance of Cl- in the response. This response to Bk was mimicked by the calcium ionophore ionomycin. Bk stimulated the formation of inositol 1,4,5-trisphosphate (IP3), and increased the release of arachidonic acid. In addition, Bk produced an increase in [Ca2+]i, as determined by microspectrofluorimetry. This was due to the release of Ca2+ from intracellular stores, since the response was unaltered when the cells were bathed in Ca(2+)-free solution. In summary, Bk depolarizes ND7/23 cells, probably through the activation of a chloride conductance. It seems likely that this is secondary to the rise in cytosolic Ca2+ concentration, due to the release of Ca2+ from internal stores by IP3. This Ca(2+)-activated chloride response is present in some sensory neurones, although its role in the activation of sensory neurones by Bk is at present unclear.
