Ion transport processes of crustacean epithelial cells

Epithelial cells of the gut, antennal glands, integument, and gills of crus taceans regulate the movements of ions into and across these structures and thereby influence the concentrations of ions in the hemolymph. Specific tr ansport proteins serving cations and anions are found on apical and basolat eral cell membranes of epithelia in these tissues. In recent years, a consi derable research effort has been directed at elucidating their physiologica l and molecular properties and relating these characteristics to the overal l biology of the organisms. Efforts to describe ion transport in crustacean s have focused on the membrane transfer properties of Na+/H+ exchange, calc ium uptake as it relates to the molt cycle, heavy metal sequestration and d etoxification, and anion movements into and across epithelial cells. In add ition to defining the properties and mechanisms of cation movements across specific cell borders, work over the past 5 yr has also centered on definin g the molecular nature of certain transport proteins such as the Na+/H+ exc hanger in gill and gut tissues. Monovalent anion transport proteins of the gills and gut have received attention as they relate to osmotic and ionic b alance in euryhaline species. Divalent anion secretion events of the gut ha ve been defined relative to potential roles they may have in hyporegulation of the blood and in hepatopancreatic detoxification events involving compl exation with cationic metals.