OBJECTIVETo determine the expression of kidney aquaporin-2 (AQP2) and urine AQP2 excretion in chronic heart failure (CHF) rats and investigate effects of perindopril on the expression and excretion of AQP2.

METHODSSixty rats were randomized into three groups: control group, CHF group, CHF + Perindopril group. According to left ventricular myocardial infarction size, CHF group and perindopril group were further divided into heart failure subgroup (LVMI ≥ 20%) and cardiac functional compensation subgroup (LVMI < 20%), respectively. Blood and urine samples were collected from the rats for measuring serum Na(+), urine volume and urine osmolality. The concentration of plasma arginine vasopressin (p-AVP) was detected by radioimmunoassay (RIA). Immunohistochemistry, semi-quantitative real time-polymerase chain reaction (RT-PCR) and Western blot were performed for measurement of kidney inner medullary AQP2. The concentration of Urine AQP2 was measured by indirect enzyme-linked immunosorbent assay (indirect ELISA).

RESULTSImmunohistochemistry, RT-PCR, Western blot examinations revealed increased quantity of the inner kidney medullary AQP2 expression (0.2013 ± 0.0417), AQP2 mRNA (0.98 ± 0.33) and AQP2 protein expression (0.94 ± 0.21) in heart failure subgroup (n = 13) compared to control group (n = 20, 0.1518 ± 0.0214, 0.58 ± 0.51, 0.51 ± 0.46), which could be significantly by perindopril (n = 13, 0.0712 ± 0.0218, 0.76 ± 0.45, 0.82 ± 0.49, all P < 0.05 vs. heart failure subgroup). The concentration of plasma arginine AVP [(19.72 ± 3.91) ng/ml] and Urine AQP2 [(82.52 ± 11.77) ng/L] were significantly higher in heart failure subgroup than in control group [n = 20, (51.67 ± 12.58) ng/L, (6.94 ± 3.10) ng/ml] (P < 0.05), which were significantly reduced by perindopril [n = 13, (15.65 ± 4.10) ng/L, (71.65 ± 9.21) ng/ml].

CONCLUSIONIncreased expression of the kidney inner medullary AQP2 and the excretion of urine AQP2 in chronic heart failure rats could be reduced by perindopril.