Aglomerular kidney function when challenged with exogenous MgSO4 loading or environmental MgSO4 depletion

M. Danielle Mcdonald, Patrick J. Walsh

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The goal of this study was to investigate the role of MgSO4 in aglomerular kidney function, independent of changes in NaCl. The renal handling of MgSO4 was manipulated by intravenous infusion of an isoosmotic solution containing 80 mmol/L MgSO4 or through exposure to an environment that was reduced in MgSO4 concentration by 90%. Intravenous infusion resulted in a transient increase in circulating Mg 2+ and SO42- levels; however, the concentration of both divalent ions in the urine remained elevated throughout the entire infusion period. Infusion also resulted in a transient increase in urine flow rate and apparent glomerular filtration rate, measured using the glomerular filtration rate marker, [3H] PEG 4000. Exposure to MgSO 4-depleted conditions resulted in a significant decrease in plasma and urine concentrations of Mg2+ and in the urine concentrations of SO42-; correspondingly, urine flow rate was significantly depressed. The urinary excretion of both Mg2+ and SO4 2- demonstrated nonlinear saturation kinetics. The urinary excretion of Mg2+ was significantly correlated with plasma Mg2+ concentration (r = 0.75, P = 0.04) and yielded a Michealis constant (K m) of 1.67 ± 1.43 mmol/L; P = 0.26 and a maximal velocity (Vmax) of 117.4 ± 47.0 μmol/kg/hr; P = 0.046. The urinary excretion of SO42- was significantly correlated with plasma SO42- concentration (r = 0.94, P < 0.02) with a Km of 0.76 ± 0.54; P = 0.26 and a Vmax of 59.3 ± 13.1; P = 0.02.

Original languageEnglish (US)
Pages (from-to)676-687
Number of pages12
JournalJournal of Experimental Zoology Part A: Ecological Genetics and Physiology
Volume307
Issue number12
DOIs
StatePublished - Dec 1 2007

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Animal Science and Zoology
  • Molecular Biology
  • Genetics

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