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Journal of Experimental Biology 143,459-473 (1989)
Published by Company of Biologists 1989

MODULATION OF SCREENING-PIGMENT POSITION IN CRAYFISH PHOTORECEPTORS BY SEROTONIN: POSSIBLE INVOLVEMENT OF Na+/K+-ATPase ACTIVITY

EUGENIO FRIXIONE 1 and JORGE HERNÁNDEZ 1

1 Departamento de Biologia Celular and Departamento de Fisiología, Bíofisica y Neurociencias, Centro de Investigatión y de Estudios Avanzados del IPN, Apartado Postal 14-740, México, DF 07000 Mexico

The possibility that serotonin might play a role in the modulation of screening-pigment position in crayfish photoreceptors was explored through experiments with isolated eyes and a membrane fraction from retinal homogenates. In the isolated eye serotonin (≥10-4 moll-1) and some of its agonists exerted a limited dark-adapting influence over the pigment position, irrespective of the presence or absence of light, and this effect was abolished by the simultaneous addition of serotonin antagonists. In the retinal membrane fraction serotonin and quipazine produced a methysergide-sensitive stimulation of the Na+/K+-ATPase activity. These results are interpreted in terms of a serotonin-mediated efferent input on the photoreceptors, which would affect the ionic regulation of the pigment transport mechanisms.

Key words: crustaceans, photoreceptors, pigment migration, serotonin, Na+/K+-ATPase

Accepted on January 4, 1989






© The Company of Biologists Ltd 1989