Regulation of paracellular ion conductances by NaCl gradients in renal epithelial cells.
In the present study, we clarified how the NaCl gradient across the epithelial cells regulates the paracellular ion conductance. Under isotonic conditions, the absorption-directed NaCl gradient elevated the paracellular conductances of Na(+) (G(Na)) and Cl(-) (G(Cl)), while the secretion-directed NaCl gradient diminished the G(Na) and G(Cl). We further investigated the paracellular ionic conductances of NMDG (G(NMDG)) and gluconate (G(gluconate)) by replacing Na(+) with NMDG or Cl(-) with gluconate. The G(NMDG) was lower than the G(Na) and the replacement of Na(+) with NMDG decreased the G(Cl). The G(gluconate) was lower than the G(Cl) and the replacement of Cl(-) with gluconate also decreased the G(Na). These observations suggest the interaction of cations and anions on paracellular ionic conductances; i.e., cations affect paracellular anion conductances and anions affect paracellular cation conductances.
Tokuda
Shinsaku
S
Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
Niisato
Naomi
N
Marunaka
Yoshinori
Y
D000465:Algorithms; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D017609:Barium Compounds / Q000494:pharmacology; D002460:Cell Line; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D002712:Chlorides / Q000378:metabolism / Q000494:pharmacology; D004553:Electric Conductivity; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D017136:Ion Transport / Q000187:drug effects; D007668:Kidney / Q000166:cytology; D008564:Membrane Potentials / Q000187:drug effects; D009579:Nitrobenzoates / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013997:Time Factors
D017609:Barium Compounds; D018118:Chloride Channels; D002712:Chlorides; D009579:Nitrobenzoates; D026902:Potassium Channel Blockers; C013407:benzamil; C024986:barium chloride; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D012965:Sodium Chloride; D000584:Amiloride; D012964:Sodium; D011188:Potassium