Abstract
This experiment was undertaken to see effects of cholinesters, some bioactive amines, amino acids, several autonomic nerve agents and some miscellaneous compounds on the isolated cockroach hindgut movement. Cholinesters produced rather mild effect than other agents, they tend to increase the coordination, frequency and amplitude of the hindgut movement, but did not induce the contraction of hindgut. Acetylcholine had high effectiveness and its threshold of effective concentration was 10-8 g/ml. Tryptamine analogues produced increases of contraction, amplitude and frequency. Contraction of hindgut was a specific action by these agents, and this contraction seemed to be good for hindgut movement. Serotonin had the highest effectiveness among all tested compounds, its threshold of effective concentration was 10-11 g/ml. Catechol and phenyl amines showed very high increases of amplitude and frequency in a short while after application, however these stimulatory actions were followed by progressive decreases of amplitude and frequency. Glutamic acid and glutamine had high stimulatory action among amino acids, their threshold of effective concentrations were about 10-8 g/ml, many other amino acids had little or no effect on the hindgut movement. The present studies involved discussion of possible receptor system.
