| Abstract: | The effect of amines on the feeding response of Hydra japonicawas determined using the tentacle ball formation assay. Manyaliphatic and aromatic amines depressed the response immediatelyupon addition to the bathing medium at final concentrationsranging from 1 nmol/l to 100 µmol/l. Examining the depressingeffect of various amines, we concluded that two kinds of aminereceptors were located on the surface of Hydra. One perceiveddopamine and D-noradrenaline, and depressed only the responseelicited by weak stimuli. Dopamine depressed the response at1 nmol/l. D,L-Propranolol was a competitive antagonist againstthis receptor. The other perceived tyramine and most of theamines examined, and depressed the response elicited by bothweak and strong stimuli. Tyramine depressed the response at1 µmol/l. D,L-Propranolol did not block its action. Afterthe animals were treated with dibenamine, both dopamine andtyramine became ineffective in depressing the response withoutinfluence on the response of the animal elicited by S-methylglutathione.
*Present address: Tokyo Laboratory of Japan Synthetic RubberCo. Kawasaki 215, Japan |
