Figure 4. Dose-dependent activation of C-MH and C-M fibres by α,β-methylene ATP in normal and inflamed skin.

In A the time course of C-MH fibre activation by α,β-methylene ATP (n = 16–21) is shown; spontaneous activity was not subtracted in this case. For clarity the activity between agonist doses is not shown (note the breaks in the abscissa). Note that in inflamed skin (□) low doses of α,β-methylene ATP induce a long-lasting increase in on-going activity in C-MH fibres that was not observed in normal skin (^). Thus the mean activity is already high in these fibres shortly before application of the second and third doses of α,β-methylene ATP. In B the equivalent data from C-M fibres are plotted (n = 5-15). Note that these fibres are much less affected by carrageenan inflammation and no significant effect was observed of low doses of agonist on on-going activity.