The body wall of the land slug Ariolimax columbianus Gould (Arionidae) secretes fluid in response to mechanical stimulation. This fluid is a product of specialized channel cells, with addition of mucus. Channel cell function can be explained in terms of ultrafiltration of blood components into the central channel, and modification of this ultrafiltrate, prior to extrusion from the body surface, by cellular transport of univalent ions but without change in osmotic pressure. Sodium and chloride ions are conserved, and potassium and bicarbonate ions are transferred out into the channel cell product. Agents known to affect epithelial transports and ion processing in a variety of animals - ouabain, amiloride, furosemide, SITS and acetazolamide - depress the function of the slug channel cells.

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