Figure 4: ASIC pharmacological antagonism has no effect upon primary (muscle) or secondary (cutaneous) hyperalgesia induced by repeated intramuscular acid injections. (a) Mean muscle withdrawal thresholds. (b) mean number of responses to repeated von Frey stimulation of the paw measured before first and second acid injections, 24 hours after second acid injection, and after intramuscular injection of A-317567 or control injection. While there was an increase in mechanical sensitivity of the paw and muscle after repeated acid injections, there was no difference in this sensitivity after intramuscular injection of the ASIC antagonist.