AQP2 and hydrops fetalis: 3) to investigate whether IM expressions of AQP2, p-AQP2 and AQP1, AQP3, and AQP4 in early-stage HF are changed compared with healthy animals under basic states and in conditions with enhanced ANG II levels and DDAVP infusion, and 4) to examine whether these changes are associated with changes in cardiac function, V2R, AT1R and the (pro)renin receptor (P)RR.