title: Electrogenic, K+-dependent chloride transport in locust hindgut.
abstract: Potassium chloride is the major salt recycled in most insect secretory systems. Ion and water reabsorption occur in the rectum by active transport of Cl- and largely passive movement of K+. Both these processes are stimulated several fold by a neuropeptide hormone acting via cyclic AMP (cAMP). This Cl- transport process was investigated by using intracellular ion-sensitive microelectrodes, radiotracer flux measurements, voltage clamping, ion substitutions and inhibitors. the mucosal entry step for Cl- is energy-requiring and highly-selective, and is stimulated directly by cAMP and luminal K+. Under some experimental conditions, measured electrochemical potentials for cations across the mucosal membrane are too small to drive C;- entry by NaCl or KCl cotransport mechanisms; moreover, net 36Cl- flux is independent of the apical Na+ potential. Similarly no evidence for a HCO3- -Cl- exchange was obtained. We conclude that Cl- transport in locust gut is different from mechanisms currently proposed for vertebrate tissues.
mesh_terms: D000818:Animals; D001693:Biological Transport, Active; D002712:Chlorides / Q000378:metabolism*; D000242:Cyclic AMP / Q000502:physiology; D006110:Grasshoppers; D006863:Hydrogen-Ion Concentration; D007422:Intestines; D007700:Kinetics; D008564:Membrane Potentials; D011188:Potassium / Q000502:physiology; D012964:Sodium / Q000378:metabolism
chemical_list: D002712:Chlorides; D012964:Sodium; D000242:Cyclic AMP; D011188:Potassium