Characterization of two MDCK-cell subtypes as a model system to study principal cell and intercalated cell properties

Abstract

Madin-Darby canine kidney (MDCK) cells originate from the renal collecting duct and consist of different cell subtypes. We cloned two MDCK cell subtypes denominated as C7 and C11 with different morphology and different function. The two clones maintained their functional differences after cloning. C7 monolayers exhibit a high transepithelial resistance (R _te=5648±206 Ω · cm², n=20) and secrete K⁺ (ΔK⁺=1.31±0.08 mmol/l, n=10) into the apical medium. C11 monolayers display a low R _te (330±52 Ω · cm², n=20) and secrete Cl⁻ (ΔCl⁻= 16.9±1.8 mmol/l, n=10) into the apical medium. Aldosterone (1 μmol/l) stimulates K⁺ secretion (ΔK⁺ of 3.58±0.11 mmol/l, n=7) in C7 cells and H⁺ secretion in C11 cells (ΔpH=0.060±0.007, n=10). Aldosterone-induced stimulation of K⁺ secretion is inhibited by apical application of amiloride (1 μmol/l). cAMP stimulates H⁺ secretion in C11 cells (ΔpH= −0.068±0.004, n=10). Furthermore, C7 cells are peanut-lectin(PNA)-negative and exhibit an intracellular pH of 7.39±0.05 (n=7), whereas C11 cells maintain intracellular pH at 7.16±0.05 (n=8) and a major fraction of cells is PNA positive. We conclude that we have cloned two subtypes of MDCK cells which stably express different functional characteristics. The C7 subtype resembles principal cells (PC) of the renal collecting duct, whereas the C11 subtype resembles intercalated cells (ICC) of the renal collecting duct. The C11 subtype seems heterogenous and possibly consists of two subpopulations similar to the α-ICC and β-ICC of the renal collecting duct. The two cloned subtypes could serve as a valuable model to study PC-like cells and ICC-like cells independently.