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Journal of Experimental Biology 62,243-265 (1975)
Published by Company of Biologists 1975

Transport of Exogenous D-glucose by the Integument of a Polychaete Worm (Nereis Diversicolor Müller)

GREGORY A. AHEARN ¹ and JRGEN GOMME ²

¹ Present address: Hawaii Institute of Marine Biology, University of Hawaii, P.O. Box 1346, Kaneohe, Hawaii 96744, U.S.A.
² August Krogh Institute, Zoophysiological Laboratory A, University of Copenhagen, 13 Universitetsparken, DK-2100 Copenhagen , Denmark

1. Integumentary exchange of radio-labelled D-glucose in the brackish-water polychaete worm Nereis diversicolor (Annelida; Polychaeta) was investigated.

2. In animals acclimated to 50% sea water, the influx of D-glucose was measured, and shown to occur largely across the outward-facing membranes of the epidermal cells.

3. Transfer of exogenous D-glucose across the outer membranes occurs by facilitated transfer, involving two different transport systems. One of these has a K_t (transport constant) of 5 µM, i.e. of the order of magnitude of environmental D-glucose concentrations. The K_t for the other system is at least ten times higher.

4. The D-glucose is rapidly metabolized by the epidermal cells. Small amounts of unmetabolized D-glucose are released to the extracellular fluid, and probably to the medium.

5. The maximal D-glucose outflux through the apical border of the epidermal cells is at least 4 times smaller than the outflux through the baso-lateral border.

6. A maximum value is given for the diffusion permeability of D-glucose through the intercellular spaces of the integument. Applying this figure, the loss by intercellular diffusion was found not to exceed the D-glucose influx into the epidermal cells.

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				H. Ahearn, G. Ahearn, and J Gomme Integumentary L-histidine transport in a euryhaline polychaete worm: regulatory roles of calcium and cadmium in the transport event J. Exp. Biol., January 9, 2000; 203(18): 2877 - 2885. [Abstract] [PDF]