Volume 67, Issue 2, Pages 613-621 (February 2005) Defining conditions that lead to the retention of water: The importance of the arterial sodium concentration  Mohammad A. Shafiee, Andre F. Charest, Surinder Cheema-Dhadli, Daniel N. Glick, Olga Napolova, Jamshid Roozbeh, Elena Semenova, Asheer Sharman, Mitchell L. Halperin  Kidney International  Volume 67, Issue 2, Pages 613-621 (February 2005) DOI: 10.1111/j.1523-1755.2005.67117.x Copyright © 2005 International Society of Nephrology Terms and Conditions

Figure 1 Urine osmolality in urines collected throughout the day. Urines were provided q2 to 3h during daytime plus overnight if the subject rose to void in all the subjects in this study. Data are shown for male (♦) and female (O) subjects. The dashed horizontal line represents the Posm at 290 mOsm/kg H2O. The time of day is shown on the x-axis and the Uosm on the y-axis. Kidney International 2005 67, 613-621DOI: (10.1111/j.1523-1755.2005.67117.x) Copyright © 2005 International Society of Nephrology Terms and Conditions

Figure 2 Representative study of a 20-mL/kg water load. The time of day in hours is shown on the x-axis, and the urine flow rate is shown on the y-axis. After obtaining a second-voided urine, the subject consumed 20mL water/kg in 15 minutes. After reaching a plateau for the urine flow rate at peak diuresis, water intake was stopped and the subject excreted only 10mL/kg before his Uosm was greater than his Posm. Kidney International 2005 67, 613-621DOI: (10.1111/j.1523-1755.2005.67117.x) Copyright © 2005 International Society of Nephrology Terms and Conditions

Figure 3 Influence of the Na + K content of the diet on the volume of water retained during the slow intake of water. The daily excretion of Na + K in mmol/day is shown on the x-axis, and the volume of water retained after slow water ingestion in mL/kg is shown on the y-axis. Data are shown for male (♦) and female (O) subjects. Subjects consuming more salt might raise their level of vasopressin more quickly when their arterialized PNa increased due to the renal excretion of a large volume of electrolyte-free water when the input from the GI tract declined. There is a direct and statistically significant relationship between these two parameters (r2= 0.63, P < 0.01). Kidney International 2005 67, 613-621DOI: (10.1111/j.1523-1755.2005.67117.x) Copyright © 2005 International Society of Nephrology Terms and Conditions

Figure 4 Fall in the PNa in arterialized and venous plasma during a 20-mL/kg water load. The time in minutes after consuming 20mL of water in <15 minutes is shown on the x-axis, and the PNa in mmol/L is shown on the y-axis. The dashed line depicts the arterialized PNa and the solid line depicts the PNa in the antecubital vein. The mean value for all control bloods is shown as the 0-time value. The results are the mean ± SEM for 7 subjects. All PNa values except the 0-time and the 60-minute times were significantly lower in the arterialized blood as compared to the venous PNa values by paired value analysis (*P < 0.01). Kidney International 2005 67, 613-621DOI: (10.1111/j.1523-1755.2005.67117.x) Copyright © 2005 International Society of Nephrology Terms and Conditions

Figure 5 Fall in the PNa in arterialized and venous plasma while sipping a 10mL/kg water load. The time in hours after beginning the consumption of the water load is shown on the x-axis, and the PNa in mmol/L is shown on the y-axis. The dashed line depicts the arterialized PNa and the solid line depicts the PNa from the antecubital vein. The mean value for all control bloods is shown as the 0-time value. The results are the mean ± SEM for 4 subjects. The PNa values were not significantly lower in the arterialized as compared to the corresponding venous values. Kidney International 2005 67, 613-621DOI: (10.1111/j.1523-1755.2005.67117.x) Copyright © 2005 International Society of Nephrology Terms and Conditions

Figure 6 Water distribution after the rapid consumption of water. When water is ingested (gray filled box on the left), it is absorbed from the intestinal tract and enters the portal vein; this leads to a large fall in the arterial PNa. When arterial blood is delivered to the brain and skeletal muscle, the muscle cells will continue to swell for a longer period than for brain cells because the mass (water content) of muscle is much larger than that of the brain, yet their blood flow rates are similar. As a result, the PNa in venous blood draining muscle will be much higher in the earlier time points before equilibrium has been reached. Kidney International 2005 67, 613-621DOI: (10.1111/j.1523-1755.2005.67117.x) Copyright © 2005 International Society of Nephrology Terms and Conditions