OBJECTIVETo investigate effects of the furosemide, antisterone and hydrochlorothiazide on expression of kidney aquaporin-2 (AQP(2)) gene and urine aquaporin-2 excretion in rats.

METHODSForty SD rats were randomized into 4 groups, namely the control group, furosemide group, antisterone group and hydrochlorothiazide group with corresponding treatment. Blood and urine samples were collected from the rats for measurement of serum Na(+), urine volume and urine osmolality during medication. Semi-quantitative RT-PCR was performed to measure kidney inner medullary AQP(2) and vasopressin V(2)-R mRNA. Western blotting was employed to detect kidney inner medullary AQP(2) protein expression. Urine AQP(2) concentration was measured by enzyme-linked immunosorbent assay (ELISA).

RESULTUrine volume and urinary AQP(2) excretion were both increased in rats treated with the 3 drugs as compared with that of the control group. However, urine osmolality was lower in furosemide group but higher inhydrochlorothiazide and antisterone groups than in the control group (P<0.05). The kidney inner medullary AQP(2) mRNA, V(2)-R mRNA and AQP(2) protein expression of furosemide group increased in comparison with that of the control group (Plt;0.05). In hydrochlorothiazide group, however, the above parameters were all decreased (Plt;0.05).

CONCLUSIONThe three classes of diuretics can all increase the excretion of the urinary AQP(2) but have different effects on the inner medullary AQP(2) mRNA and protein expression in normal rats. Hydrochlorothiazide reduces kidney AQP(2) mRNA and protein expression, while furosemide increased kidney AQP(2) gene expression.