Fig. 4.

Summary data showing that the responses to capsaicin of group III and IV afferents were not reduced by DAMGO in either “freely perfused” or “ligated rats.” Black vertical bars represent mean values for the 30 s of control preceding capsaicin injection, whereas the gray vertical bars represent mean values for the 30 s following capsaicin (0.2 µg) injection into the superficial epigastric artery. Vertical brackets over each bar represent the standard error of the mean. Injecting DAMGO (1 µg) into the superficial epigastric artery did not significantly change the response in afferent fibers from freely perfused (A, B) or ligated (C, D) rats. *P < 0.05, **P < 0.01, ***P < 0.001 vs. capsaicin for same condition.