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This Article Full Text Full Text (PDF) All Versions of this Article: 92/1/251    most recent expphysiol.2006.034751v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Chamberlain, R. M. Articles by Shirley, D. G. Search for Related Content PubMed PubMed Citation Articles by Chamberlain, R. M. Articles by Shirley, D. G.

¹ Department of Physiology and Centre for Nephrology, Royal Free & University College School of Medicine, London, UK

Previous investigations into the functional responses of the surviving nephrons following reductions in renal mass have been performed largely in anaesthetized animals and have taken little account of how the compensatory changes develop with time. The present study has assessed a method for determining glomerular filtration rate (GFR) in unrestrained, uncatheterized, conscious rats (plasma disappearance of ^99mTc-diethylenetriamene pentaacetic acid (DTPA)) and has used this method to document the time course of the changes in GFR over a 32 day period following uninephrectomy or 5/6 nephrectomy. Concurrent measurements of excretion rates and of the clearance of lithium (the latter being an index of end-proximal fluid delivery) provided information on changes in overall tubular function and segmental reabsorption. After uninephrectomy, the GFR of the remaining kidney (compared with that of a single kidney of sham-operated animals) increased maximally (by 50%) within 8 days; after 5/6 nephrectomy, the increase in the GFR of the remnant kidney was maximal (at 300%) within 16 days. Overall excretion rates of sodium and potassium were well maintained in partially nephrectomized animals throughout the period of study, while the excretion of water increased (by 30% after uninephrectomy and by 120% after 5/6 nephrectomy), partly as a result of the compensatory increases in GFR but mainly as a consequence of moderate (after uninephrectomy) or marked (after 5/6 nephrectomy) reductions in fractional reabsorption. During the early period after 5/6 nephrectomy, potassium excretion sometimes exceeded the filtered load, indicating net secretion. Lithium clearance data indicated that the changes in tubular function after 5/6 nephrectomy include a reduction in fractional reabsorption in the proximal tubule, whereas after uninephrectomy any such effect on the proximal tubule is minor and transient.

(Received 15 June 2006; accepted after revision 30 October 2006; first published online 3 November 2006)
Corresponding author D. G. Shirley: Department of Physiology and Centre for Nephrology, Royal Free & University College School of Medicine, Hampstead Campus, Rowland Hill Street, London NW3 2PF, UK. Email: david.shirley{at}ucl.ac.uk