Factors Influencing Sodium Reabsorption in the Distal Nephron

Summary

In 16 of 25 studies during hypotonic sodium sulfate infusion, the development of a chloruresis was temporally associated with a maximal level of CH₂O In nine studies, no chloride diuresis developed, and CH₂O remained lower than in the former group despite the attainment of similar levels of solute excretion and urine flow rate. With renal-artery constriction, a close relationship was also demonstrated between the level of CH₂O and the supply of sodium chloride to the distal nephron. The level of CH₂O attained did not relate to levels of solute excretion, urine, flow rate, or intratubular chloride concentration. However, a direct linear relationship was observed between the maximal level of CH₂O and GFR over a range of GFR from 15 to 51 ml/min. These findings support the view that a maximal level of CH₂O represents a limit in sodium chloride reabsorption in the distal nephron and suggest that the capacity of the distal nephron to reabsorb sodium chloride is influenced by those factors determining the glomerular filtration rate.

We thank Mrs. Sarah Bogert for her technical assistance. This work was supported by Public Health Service Training Grant HE 5-5505 and a grant from the New York Kidney Foundation.