Abstract
Summary
1. When the plasma sodium concentration is progressively elevated in dogs by the administration of hypertonic saline, the rate of renal tubular reabsorption of sodium remains constant in those experiments where the glomerular filtration rate is not significantly affected. If the filtration rate increases or decreases in response to the hypertonic saline, the rate of sodium transport deviates in the same direction. Therefore, in experiments where the sodium level is elevated for a period of one hour or less, any alteration in the rate of sodium transport is dependent upon the concomitant change in filtration rate. 2. Hypertonic saline exerts a profoundly depressant effect upon the PAH Tm, and a significant but less marked influence upon the glucose Tm. This depression is believed to be nonspecific in nature and contra-indicates the use of these determinations as an index of effective tubular mass in experiments in which variations in sodium concentration are involved.
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