title: L-arginine effects on Na+ transport in M-1 mouse cortical collecting duct cells--a cationic amino acid absorbing epithelium.
abstract: The effect of L-arginine on transepithelial ion transport was examined in cultured M-1 mouse renal cortical collecting duct (CCD) cells using continuous short circuit current (Isc) measurements in HCO3-/CO2 buffered solution. Steady state Isc averaged 73.8 +/- 3.2 microA/cm2 (n = 126) and was reduced by 94 +/- 0.6% (n = 16) by the apical addition of 100 microM amiloride. This confirms that the predominant electrogenic ion transport in M-1 cells is Na+ absorption via the epithelial sodium channel (ENaC). Experiments using the cationic amino acid L-lysine (radiolabeled) as a stable arginine analogue show that the combined activity of an apical system y+ and a basal amino acid transport system y+L are responsible for most cationic amino acid transport across M-1 cells. Together they generate net absorptive cationic amino acid flux. Application of L-arginine (10 mM) either apically or basolaterally induced a transient peak increase in Isc averaging 36.6 +/- 5.4 microA/cm2 (n = 19) and 32.0 +/- 7.2 microA/cm2 (n = 8), respectively. The response was preserved in the absence of bath Cl- (n = 4), but was abolished either in the absence of apical Na+ (n = 4) or by apical addition of 100 microM amiloride (n = 6). L-lysine, which cannot serve as a precursor of NO, caused a response similar to that of L-arginine (n = 4); neither L-NMMA (100 microM; n = 3) nor L-NAME (1 mM; n = 4) (both NO-synthase inhibitors) affected the Isc response to L-arginine. The effects of arginine or lysine were replicated by alkalinization that mimicked the transient alkalinization of the bath solution upon addition of these amino acids. We conclude that in M-1 cells L-arginine stimulates Na+ absorption via a pH-dependent, but NO-independent mechanism. The observed net cationic amino acid absorption will counteract passive cationic amino acid leak into the CCD in the presence of electrogenic Na+ transport, consistent with reports of stimulated expression of Na+ and cationic amino acid transporters by aldosterone.
authors.affiliation: University Laboratory of Physiology, Oxford University, UK.
authors.forename: D P
authors.initials: DP
authors.lastname: Howard
authors.forename: J E
authors.initials: JE
authors.lastname: Cuffe
authors.forename: C A
authors.initials: CA
authors.lastname: Boyd
authors.forename: C
authors.initials: C
authors.lastname: Korbmacher
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D002460:Cell Line; D016764:Cell Polarity; D004232:Diuretics / Q000494:pharmacology; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D006639:Histidine / Q000494:pharmacology; D017136:Ion Transport / Q000187:drug effects; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D008239:Lysine / Q000737:chemistry / Q000494:pharmacology; D051379:Mice; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D026423:S-Nitroso-N-Acetylpenicillamine; D012964:Sodium / Q000378:metabolism*; D019459:Urothelium / Q000166:cytology / Q000378:metabolism*; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D004232:Diuretics; D004791:Enzyme Inhibitors; D019323:omega-N-Methylarginine; D006639:Histidine; D026423:S-Nitroso-N-Acetylpenicillamine; D000584:Amiloride; D001120:Arginine; D012964:Sodium; D010396:Penicillamine; D008239:Lysine