There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
A novel modification of the stimulated cobalt uptake technique has been used to identify
rat dorsal root ganglion cells expressing capsaicin and bradykinin receptors. The
technique involves incubating intact dorsal root ganglia in vitro in a modified Krebs
solution in which cobalt chloride has been substituted for calcium. Activation of
dorsal root ganglion cells by capsaicin or bradykinin in the presence of the cobalt
ions results in cobalt influx into the excited cells. Histochemical methods were then
used to visualize the intracellular accumulation of cobalt, and labelled cells were
counted and characterized. Capsaicin (2 microM) or bradykinin (500 nM) applied for
20 min induced cobalt uptake in 13.8 +/- 0.6 and 9.6 +/- 0.5% of neuronal profiles
in dorsal root ganglia (L4), respectively, a significantly larger number than stained
in control ganglia (in the absence of agonists: 1.8 +/- 0.7%). The longest diameter
of the soma of stained dorsal root ganglion cells following capsaicin and bradykinin
perfusion were significantly different from each other and from the non-labelled population
(17.5 +/- 0.7 and 24.5 +/- 0.2 microns for capsaicin; 23.2 +/- 0.9 and 25.5 +/- 0.4
microns for bradykinin; labelled and non-labelled cells, respectively). The distribution
of cell diameters revealed that while capsaicin-sensitive cells were exclusively small-sized,
bradykinin-sensitive cells were predominantly small and medium sized. The selective
bradykinin-2 receptor antagonist HOE-140 (5.0 microM) blocked the bradykinin-induced
staining (2.16 +/- 0.02%) but not that of capsaicin. The bradykinin-1 agonist [des-Arg9]-bradykinin
did not induce any significant increase in stained cells over the control number (2.2
+/- 0.7%).(ABSTRACT TRUNCATED AT 250 WORDS)