Effect of intravenous sodium loading on renal tubular handling of sodium and water in unilaterally nephrectomized humans.
Glomerular filtration rate (GFR), proximal absolute and fractional reabsorption of isotonic fluid (PAR and PFR) and distal absolute and fractional reabsorption of sodium (DARNa and DFRNa) were measured using the lithium clearance technique in nine unilaterally nephrectomized people (UNP) 1-11 years postnephrectomy and in 14 controls before, during and after an intravenous sodium load. Glomerular filtration rate per kidney was 53% higher in UNP and decreased slightly but significantly (p less than 0.01) in both groups during sodium loading. The PAR per kidney was significantly higher in UNP (p less than 0.01) but PFR was the same as in controls. Both groups responded to sodium loading with a significant decrease in both PAR and PFR. In UNP, DARNa per kidney was significantly higher than in controls (p less than 0.01) but DFRNa was the same in the two groups. Sodium loading resulted in a further increase in DARNa and a decrease in DFRNa in both groups. Both groups responded to sodium loading with a similar increase in fractional sodium excretion. It is concluded that unilateral nephrectomy is followed by an increase in GFR, PAR and DARNa but with maintenance of fractional reabsorption in both proximal and distal tubuli. In response to an intravenous sodium load, the remnant kidney is able to respond in a normal way with a further increase in DARNa. The adjustments necessary to maintain sodium balance after unilateral nephrectomy take place in both proximal and distal tubuli.
D000328:Adult; D001834:Body Water / Q000378:metabolism*; D002860:Chromium Radioisotopes / Q000378:metabolism; D002951:Citrates / Q000378:metabolism; D019343:Citric Acid; D004492:Edetic Acid / Q000378:metabolism; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006801:Humans; D007275:Injections, Intravenous; D007684:Kidney Tubules / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000008:administration & dosage*
D002860:Chromium Radioisotopes; D002951:Citrates; D019343:Citric Acid; D012965:Sodium Chloride; D004492:Edetic Acid; D012964:Sodium