A study was made of the effect of total ureteral occlusion on renal function in 27 mongrel dogs weighing 5-12.5kg (Fig. 1).<br>Total unilateral ureteral occlusion was performed in 23 dogs, and the intrapelvic pressure was measured. Intravenous infusion of normal saline with 1.6-9.0ml/h/kg body weight caused the intrapelvic pressure to rise and reach a constant level in 61.3±12.0 (S. D.) minutes. The intrapelvic pressure at this stage was 61.8±14.7 (S. D.) mmHg (Fig. 2).<br>At the time when the elevated intrapelvic pressure became mostly stable, the glomerular filtration and tubular PAH secretion were investigated. At the stage when the elevated intrapelvic pressure became mostly stable, 18 dogs were injected intravenously with 150mg of Inulin per kg of body weight and 4mg of PAH per kg of body weight, and sacrificed 1 hour later. Inulin and PAH were demonstrated in the pelvic urine on the occluded side of all the 18 dogs. The Inulin and PAH amounts found in the pelvic urine on the occluded side were 29.3±14.0 (S. D.) % and 35.5±16.3 (S. D.) % of the counterparts in the contralateral normal kidney (Table 1 and 2).<br>The bilateral renal blood flows were simultaneously measured in 11 dogs. The renal blood flow on the occluded side increased as the intrapelvic pressure rose after occlusion of the ureter (Fig. 3). The renal blood flow increased by 22.5% on the average over the control flow 30 minutes after occlusion of the ureter, and by 34.6% on the average at the stage when the elevated intrapelvic pressure became stable.<br>Three kinds of parameters were used to observe the effect of total ureteral occlusion on the contralateral renal function: renal blood flow, glomerular filtration rate and urine volume.<br>The contralateral renal blood flow increased by 4.1% on the average over the control flow 30 minutes after occlusion of the left ureter, and by 10.8% on the average at the stage when the elevated intrapelvic pressure became mostly stable.<br>The endogenous creatinine clearance was measured in 21 dogs as an index to the glomerular filtration rate. The contralateral renal glomerular filtration rate was decreased to 81.8% of the control rate on the average during the stage when the elevated intrapelvic pressure remained stable (Table 3).<br>In 18 dogs were measured the control urine volume of both side, the urine volume from right kidney during the first 30 minutes following left ureteral occlusion, the urine volume from right kidney during the period when the left intrapelvic pressure was elevated and became stable, the urine volume from right kidney during the first 30 minutes after injection of Inulin and PAH, and the urine volume during the second 30 minutes after injection of Inulin and PAH. The urine volume tended to increase slightly after occlusion of the ureter (Fig. 4). The percentages of the urine volume during the above-mentioned periods to control urine volume averaged 115.4%, 107.7%, 123.1% and 123.1%, respectively.<br>The mean aortic blood pressure was continuously measured during the experiment, as shown in figure 5. The pressure in no way altered in any of the animals.<br>From the above-presented results of experiment, it was demonstrated that even during the stage when the intrapelvic pressure was elevated due to total ureteral occlusion, and remained mostly stable the glomerular filtration and tubular PAH secretion proceeded in the kidney on the occluded side. Considering pyelovenous and pyelolymphatic backflows, it may be presumed that the glomerular filtration and tubular PAH secretion are carried out actively in the kidney on this side.<br>There was no significant difference between values of the 3 parameters measured during the control stage and that after occlusion of the ureter. Thus, the effect of total ureteral occlusion on the kidney on the contralateral side was not clear.