Objective The renal hemodynamic alteration was sequentially studied in dogs with ascites due to portal hypertension.Methods The model of portal hypertension was established by the constriction of hepatic vein. Effective renal plasma flow (ERPF), systemic blood pressure, urinary excretion of sodium were measured. Eighteen dogs were studied until the ascites occurred.Results The ascites was generally detected between the sixth day and the eighth day after the portal hypertension occurred, the average being the seventh day. Mean artery pressure (MAP) and renal vascular resistance (RVR) were firstly changed after the portal vein pressure increased. MAP fell 17% (130.37mmHg±16.2 mmHg before the portal hypertension, 108.32 mmHg±10.47 mmHg after the portal hypertension on the 1st day, p<0.001) and RVR increased by 31% (0.38 mmHg. ml~(-1). min~(-1)±0.09 mmHg. ml~(-1). min~(-1) before the portal hypertension, 0.5 mmHg. ml~(-1). min~(-1)±0.15mmHg. ml~(-1). min~(-1) after the portal hypertension, P<0.05) after the portal hypertension occurred on the 2nd day, thereafter, MAP decreased and RVR increased continually. ERPF also fell in the forepart, but there was only significant difference in the appearance of ascites (P<0.05). Urinary excretion of sodium gradually fell after portal hypertension and reached the lowest value on the 7th day, and there was statistical significance from the 2nd day (59.86 mmol/min±25.96 mmol/min before portal hypertension, 31.95 mmol/min±18.79mmol/min after the portal hypertension on the 2nd day, p<0.05).Conclusion Our research indicates that the hemodynamics has been changed before the ascites occurred. The earliest change occurs in MAP and RVR, but no marked change is found in ERPF. Objective The renal hemodynamic alteration was successively studied in dogs with ascites due to portal hypertension. Methods The model of portal hypertension was established by the constriction of hepatic vein. Effective renal plasma flow (ERPF), systemic blood pressure, urinary excretion of sodium were measured Eighteen dogs were studied until the ascites occurred. Results The ascites was generally detected between the sixth day and the eighth day after the portal hyperthyroidism, the average being the seventh day. Mean artery pressure (MAP) and renal vascular resistance (RVR) MAP fell 17% (130.37 mmHg ± 16.2 mmHg before the portal hypertension, 108.32 mmHg ± 10.47 mmHg after the portal hypertension on the 1st day, pO.001) and RVR increased by 31% ( Ml ~ (-1) ± 0.09 mmHg. Ml ~ (-1). Min ~ (-1) before the portal hypertension, 0.5 mmHg · ml ~ (-1) (-1) ± 0.15mmHg. Ml ~ (-1). Min ~ (-1) after the portal hypertens ion, P <0.05) after the portal hypertrophy on the 2nd day, thereafter, MAP decreased and RVR increased continually. ERPF also fell in the forepart, but there was only significant difference in the appearance of ascites (P <0.05) excretion of sodium gradually fell after portal hypertension and reached the lowest value on the 7th day, and there was statistical significance from the 2nd day (59.86 mmol / min ± 25.96 mmol / min before portal hypertension, 31.95 mmol / min ± 18.79 mmol / min after the portal hypertension on the 2nd day, p <0.05) .Conclusion Our research indicates that the hemodynamics has been changed before the ascites occurred. The earliest change occurs in MAP and RVR, but no marked change is found in ERPF.