Sevoflurane anaesthesia causes a transient decrease in aquaporin-2 and impairment of urine concentration.

Sevoflurane anaesthesia is occasionally associated with polyuria, but the exact mechanism of this phenomenon has not been clarified. Aquaporin-2 (AQP2) is an arginine vasopressin (AVP)-regulated water channel protein localized to the apical region of renal collecting duct cells and is involved in the regulation of water permeability. To elucidate the effect of sevoflurane anaesthesia on urine concentration and AQP2, we have compared serum and urinary concentrations of AVP, AQP2 and osmolar changes during sevoflurane and propofol anaesthesia. General anaesthesia was induced with sevoflurane or propofol in 30 patients for a variety of major surgical procedures. Blood and urine samples were obtained from patients at baseline, and 90 and 180 min after induction of anaesthesia. AVP and AQP2 concentrations were measured by radioimmunoassay. In both groups, plasma and urinary concentrations of AVP increased similarly during anaesthesia although plasma osmolality remained unchanged. Although urinary AQP2 excretion in the propofol group increased together with changes in plasma and urinary AVP, urinary AQP2 was significantly lower at 90 min in the sevoflurane group. Urine osmolality in the sevoflurane group also showed a transient but significant decrease in parallel with suppression of AQP2. Our data suggest that sevoflurane anaesthesia transiently produced an impaired AQP2 response to an increase in intrinsic AVP.