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Updated: Jan 24, 2026

Use of the Ramsay Assay to Measure Fluid Secretion and Ion Flux Rates in the Drosophila melanogaster Malpighian Tubule
Published on: November 25, 2015
secCl is a cys-loop ion channel necessary for the chloride conductance that mediates hormone-induced fluid secretion
Daniel Feingold1, Laura Knogler2,3, Tanja Starc4
1Department of Biology, McGill University, 1205 Dr. Penfield, Montréal, Québec, H3A 1B1, Canada.
Abstract:
Organisms use circulating diuretic hormones to control water balance (osmolarity), thereby avoiding dehydration and managing excretion of waste products. The hormones act through G-protein-coupled receptors to activate second messenger systems that in turn control the permeability of secretory epithelia to ions like chloride. In insects, the chloride channel mediating the effects of diuretic hormones was unknown. Surprisingly, we find a pentameric, cys-loop chloride channel, a type of channel normally associated with neurotransmission, mediating hormone-induced transepithelial chloride conductance. This discovery is important because: 1) it describes an unexpected role for pentameric receptors in the membrane permeability of secretory epithelial cells, and 2) it suggests that neurotransmitter-gated ion channels may have evolved from channels involved in secretion.
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