Abstract
Mean blood pressure, renal clearances of electrolytes and urinary volume, in addition to renal hemodynamics and functions, were comparatively investigated in rats subjected to ureteral catheterization by the ventral and the retro-peritoneal approach procedures in order to determine the validity of each of these procedures. From 60 min after the operation, the mean blood pressure in the case of ventral approach gradually decreased, while the pressure in the case of retroperitoneal approach remained constant. The urinary volume and the urinary sodium excretion in the case of the ventral approach decreased about a half in comparison with those in the retroperitoneal one, although the plasma sodium concentration was well maintained in both cases. The renal hemodynamics and functions remained normal in both cases. The decrease of urinary volume and urinary sodium excretion observed in the case of the ventral approach is considered to be due to the homeostatic protection against loss of body fluid as well as against the decrease of pressure in the abdominal cavity, both of which are caused by the opening of the abdominal cavity. It is accordingly considered that the retro-peritoneal approach procedure should be adopted for pharmacological and pharmacokinetical studies on the clearances of electrolytes and water in comparison with the clearance (s) of drug (s).
