Quantitative estimation of transmembrane ion transport in rat renal collecting duct principal cells.
Kidney collecting duct principal cells play a key role in regulated tubular reabsorption of water and sodium and secretion of potassium. The importance of this function for the maintenance of the osmotic homeostasis of the whole organism motivates extensive study of the ion transport properties of collecting duct principal cells. We performed experimental measurements of cell volume and intracellular sodium concentration in rat renal collecting duct principal cells from the outer medulla (OMCD) and used a mathematical model describing transmembrane ion fluxes to analyze the experimental data. The sodium and chloride concentrations ([Na+]in = 37.3 ± 3.3 mM, [Cl-]in = 32.2 ± 4.0 mM) in OMCD cells were quantitatively estimated. Correspondence between the experimentally measured cell physiological characteristics and the values of model permeability parameters was established. Plasma membrane permeabilities and the rates of transmembrane fluxes for sodium, potassium and chloride ions were estimated on the basis of ion substitution experiments and model predictions. In particular, calculated sodium (PNa), potassium (PK) and chloride (PCl) permeabilities were equal to 3.2 × 10-6 cm/s, 1.0 × 10-5 cm/s and 3.0 × 10-6 cm/s, respectively. This approach sets grounds for utilization of experimental measurements of intracellular sodium concentration and cell volume to quantify the ion permeabilities of OMCD principal cells and aids us in understanding the physiology of the adjustment of renal sodium and potassium excretion.
Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia. ilyaskin@bionet.nsc.ru.
Alexander V
AV
Ilyaskin
Denis I
DI
Karpov
Dmitriy A
DA
Medvedev
Alexander P
AP
Ershov
Galina S
GS
Baturina
Liubov E
LE
Katkova
Evgeniy I
EI
Solenov
D000818:Animals; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability; D048429:Cell Size; D002712:Chlorides / Q000032:analysis; D005452:Fluoresceins / Q000737:chemistry; D006706:Homeostasis; D017136:Ion Transport; D007477:Ions / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism; D007679:Kidney Medulla / Q000378:metabolism; D007685:Kidney Tubules, Collecting / Q000378:metabolism / Q000473:pathology*; D008856:Microscopy, Fluorescence; D008962:Models, Theoretical; D009995:Osmosis; D010539:Permeability; D011188:Potassium / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000032:analysis; D000254:Sodium-Potassium-Exchanging ATPase; D013997:Time Factors
D002712:Chlorides; D005452:Fluoresceins; D007477:Ions; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium; C007740:fluorexon