title: The role of Na+-H+ exchange in fluid and solute transport in the rat efferent ducts.
abstract: In vivo microperfusion techniques were used to investigate the role of Na+-H+ exchange in the efferent ducts of the rat. Individual efferent ducts were perfused with a Krebs-Ringer bicarbonate solution (KRB) containing 0, 1, 3, 5 or 7.5 mM amiloride. Concentrations of 1-5 mM amiloride inhibited fluid reabsorption from the efferent ducts in a linear dose-dependent manner with an apparent Km of 3 mM. Inhibition was maximal at 5 mM with reabsorption reduced by about 70 %. The effects of amiloride were completely reversible and there was little effect of amiloride on luminal osmolality and concentrations of Na+, Cl- or K+. It is concluded that Na+-H+ exchange is one of the principal mechanisms responsible for fluid and electrolyte reabsorption in the efferent ducts and offers a means by which the efferent ducts are able to achieve flow-dependent, autoregulated fluid reabsorption.
authors.affiliation: Department of Biological Sciences, University of Newcastle, NSW 2308, Australia.
authors.forename: L A
authors.initials: LA
authors.lastname: Hansen
authors.forename: J
authors.initials: J
authors.lastname: Clulow
authors.forename: R C
authors.initials: RC
authors.lastname: Jones
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D017136:Ion Transport / Q000187:drug effects; D008297:Male; D010477:Perfusion; D011522:Protons; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*; D013737:Testis / Q000187:drug effects / Q000378:metabolism*
chemical_list: D011522:Protons; D017923:Sodium-Hydrogen Exchangers; D000584:Amiloride; D012964:Sodium