Biophysical characterization of water transport in cultured collecting duct cells

CHARA OSVALDO; RIVAROLA VALERIA; FORD PAULA; PARISI MARIO; CAPURRO CLAUDIA

Buenos Aires, Argentina

Congreso; XIV International Biophysics Congress; 2002

IUPAB - SAB

The aim of this work was to study the hydraulic permeability of a rat cortical collecting duct cell line (RCCD1). We evaluated the transepithelial volume flow (Jw) and water permeability after cxposition to a range of hydrostatic pressure (DP) or osmolality (DP). Jw was minute by minute recorded in RCCDl monolayers cultivated on permeable supports. Jw was lineal with the DP generated; the hydrostatic permeability coefficient (Phidr, cm/s) was 1.053 ± 0.126 (n=4). Phidr was independent of Na and will not be associated to active transpot since it was not modified by ouabain or CNK. When a DP was generated increasing serosal osmolality, Jw was lineal with a osmotic permeability coeffícient (Posm x 10" cm/s) of 4.71 ± 0.41 (n=6) which was inhibited in the absence of Na (56 %), in the presence of ouabain (77%) or CNK (35%), indicating that Posm is associated to active ion transport. When osmolality was increased in the mucosal compartment Posm was significantly lower that in the above mentioned case (2.30 ± O 09. n=3. p< 0.001) indicating an asymmetry between mucosal and serosal permeability. Moreover, since Posm is dependent of active transport while Phidr does not, and considering that it is generally accepted that DP induces a paraccllular Jw, we suggest that DP induces a predominant transcellular water flux, not mediated by water channels since they are not expressed in this system