Fig. 5. Quantitative summary of effects of NOS inhibitors on peristalsis (A) and representative effects of NOS inhibitors on the behaviour of whole colonies (B,C). (A) Histogram showing the actions of NOS inhibitors on peristalsis as well as the interactions between NOS inhibitors and conventional transmitter effects (see Results). Statistical significance: ^**P<0.01 with a paired t-test. There was no significant difference between 0.1 and 1.0 mmol l^-1 L-NAME (N()-nitro-L-arginine methyl ester) or between melatonin alone and with aminoguanidine. N=6 (L-NAME), 3 (D-NAME), 5 (aminoguanidine), 4 (melatonin/aminoguanidine and GnRH/aminoguanidine). (B) Injection of L-NAME in the left half of a contracted colony led to a relaxed state relative to the control (right) half. (C) Injection of aminoguanidine in the left half of a relaxed colony led to a contracted state relative to the control half. Black line indicates the position of the axial canal.