William I. Rosenblum

Action of Biogenic Amines, Amine Oxidase Inhibitors, and Other Agents on Chromatophores of Squid, Loligo pealii.

Summary and conclusions (1) The multicellular system that controls chromatophores of Loligo pealii has been a useful tool for study of smooth muscle function in non-narcotized living animals. (2) Acetylcholine opened chromatophores. The following compounds closed them: Monamine-serotonin. tryptamine HCl, tyramine HCl; indoles-LSD 25; monamine oxidase inhibitors-iproniazid, PIH, Ro-5-0700; autonomic blockers-chlorpromazine; competitors for choline esterase-eserine sulfate. (3) Diamine, histamine dihydrochloride, had no effect. Other monamines, L-lysine and L-alanine, had no effect in comparable dosage. Catechol amines epinephrine and norepinephrine were ineffective. A precursor of serotonin, 5-hydroxytryptophan, had no effect. (4) Closure of chromatophores by an active substance was not reversible by electrical stimulation. (5) Attention is called to the fact that constricting agents all share a common property, that of resonance, and that a number of them are capable of electron donation. (6) Results obtained are consonant with theory that chromatophore control is achieved by an amine-amine oxidase system (closure), opposed by an acetylcholine-choline esterase system (expansion).