Fig. 1
Effects of neural activity and prostaglandin (PG) production on the giant contractions (GCs) of circular muscle (CM) in the rat middle colon. After equilibration, spontaneous GCs were observed and basal GCs recorded (a and b, basal period). The neural blocker TTX (10−6 mol L−1; a) or the COX inhibitor piroxicam (10−6 mol L−1; b) was then added to the organ bath, and from 10 min after its addition, the GCs in the presence of TTX (a) or piroxicam (b) were recorded for 20 min as the first period. Piroxicam (a) or TTX (b) was then added, and from 10 min after its addition, GCs were recorded for 20 min as the second period. Finally, CCh was added to the organ bath to normalize the GC amplitude. Representative traces of GCs during TTX → piroxicam treatment (a) and piroxicam → TTX treatment (b), and changes in the mean frequencies (c) and amplitudes (d) are expressed as means ± SE (TTX → piroxicam, n = 8; piroxicam → TTX, n = 6). *P < 0.05, **P < 0.01, and ***P < 0.001 indicate significant differences from the basal values, and †P < 0.05 and ††P < 0.01 indicate significant differences from the first period values, by paired t test with Holm’s correction