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

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

San Francisco - Estados Unidos

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 (JV) as well as to determine whether these processes could be affected by Aquaporins (AQPs) expression. Two cell lines were used: one not expressing AQPs (WT-RCCD1) and other transfected with AQP2 (AQP2-RCCD1). Cell volume regulation was evaluated using a videomicroscopy technique and Jv recorded with an automatically device. Results show that basolateral hypertonic shocks elicit higher JV values compared with those observed increasing luminal osmolality. This JV rectification phenomenon is independent of AQP2 expression and would be associated with activation of regulatory volume (RV) increase mechanisms. Hypotonic shocks only induced JV rectification in the presence of AQP2 and JV was higher increasing luminal osmolality. RV decrease also occurs and the activation of these mechanisms is more rapid in AQP2 cells. We conclude that the pattern of polarisation of AQPs and RV transporters as well as their activation would be critical for modulating transepithelial water transport in physiological states.