Asymmetry in the osmotic response of collecting duct cell: Role of aquaporin-2.

C . CAPURRO; O. CHARA; V . RIVAROLA; M . PARISI; P. FORD

San diego, C.A, USA

Congreso; XXXV International Congress of Physiological Sciences; 2005

American society of Physiology

The aim of this work was to study, after asymmetrical hyper or hypotonic challenges, cell volume regulation and its consequences on transepithelial volume flux (J) as well as to determine whether these processes could beaffected by Aquaporins (AQPs) expression. Two cell lines were used: one not expressing AQPs (WT-RCCD1) andother transfected with AQP2 (AQP2-RCCD1). Cell volume regulation was evaluated using a videomicroscopytechnique and Jvrecorded with an automatically device. Results show that basolateral hypertonic shocks elicithigher JVvalues compared with those observed increasing luminal osmolality. This Jrectification phenomenon isindependent of AQP2 expression and would be associated with activation of regulatory volume (RV) increasemechanisms. Hypotonic shocks only induced JVrectification in the presence of AQP2 and JV was higherincreasing luminal osmolality. RV decrease also occurs and the activation of these mechanisms is more rapid in AQP2 cells. We conclude thatthe pattern of polarisation of AQPs and RV transporters as well as their activationwould be critical for modulating transepithelial water transport in physiological states.