Fig. 3.
Response of group IV afferents to muscle stimulation in healthy Sprague Dawley rats. A) The changes in spontaneous activity of group IV afferents elicited by muscle stimulation are studied in control condition (closed circles: n = 37 units) and after intramuscular injection of SOD (open circles: n = 32 units). B) H2O2 injection before muscle stimulation markedly increased the baseline discharge rate but the response to muscle stimulation was not accentuated compared to control condition (n = 33 units). Dashed vertical bars indicate the 1-min muscle stimulation. Asterisk denote significant changes in averaged discharge rate (f impulses) measured prior to beginning muscle stimulation (*p < 0.05; **p < 0.01). Symbol $ indicates that the averaged resting discharge rate was significantly lower in rats pre-treated with SOD ($p < 0.05) and markedly higher after H2O2 injection ($ $p < 0.01).