title: Tubular sodium handling and tubuloglomerular feedback in compensatory renal hypertrophy.
abstract: Tubular sodium handling and tubuloglomerular feedback (TGF) activity were assessed in established compensatory renal hypertrophy in Sprague Dawley rats. Hyperfiltration at the level of the single nephron was confirmed 4-6 weeks following a reduction in renal mass. TGF activity, determined as the difference between late proximal and early distal measurements of single-nephron glomerular filtration rate (SNGFR), was significantly increased in compensatory renal hypertrophy, being 7.8 +/- 1.0 vs 23.3 +/- 1.9 vs 25.5 +/- 2.6 nl/min (P for analysis of variance less than 0.05) following sham operation, unilateral nephrectomy, and 1 1/3 nephrectomy, respectively. Enhanced net tubular Na transport was also observed, with total Na reabsorption up to the late proximal site being 1.8 +/- 0.2 vs 2.7 +/- 0.1 vs 3.1 +/- 0.3 nmol/min (P less than 0.05), and to the early distal site being 3.4 +/- 0.5 vs 5.8 +/- 0.6 vs 7.9 +/- 0.8 nmol/min (P less than 0.05) in the three animal groups respectively. Comparison of proximal tubular length demonstrated a 71.9 +/- 8.1% increase in uninephrectomised vs sham-operated animals. This increase was proportionately greater than the increase in proximal Na reabsorption (50.0 +/- 4.0%) observed in the corresponding animal groups. Concurrent electron microprobe experiments in uninephrectomised and sham-operated animals demonstrated that the proximal tubular intracellular Na concentration was significantly lower following uninephrectomy (16.8 +/- 0.6 vs 18.9 +/- 0.5 mmol/kg wet weight, P less than 0.01), in association with evidence of reduced basolateral Na/K-ATPase activity.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, University of Sydney, NSW, Australia.
authors.forename: C A
authors.initials: CA
authors.lastname: Pollock
authors.forename: T E
authors.initials: TE
authors.lastname: Bostrom
authors.forename: M
authors.initials: M
authors.lastname: Dyne
authors.forename: A Z
authors.initials: AZ
authors.lastname: Györy
authors.forename: M J
authors.initials: MJ
authors.lastname: Field
mesh_terms: D000818:Animals; D004577:Electron Probe Microanalysis; D005246:Feedback / Q000502:physiology; D006984:Hypertrophy; D007668:Kidney / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D007678:Kidney Glomerulus / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D007687:Kidney Tubules, Proximal / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D008297:Male; D011677:Punctures; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*
chemical_list: D012964:Sodium