Effect of phosphorus restriction on renal response to oral and intravenous protein loads in rats

Am J Physiol. 1993 Apr;264(4 Pt 2):F752-9. doi: 10.1152/ajprenal.1993.264.4.F752.

Abstract

Dietary phosphorus restriction ameliorates renal injury in rats. This may be due to changes in renal hemodynamics, including those factors associated with protein-induced hyperfiltration. To test this, we measured inulin clearance (CIn), p-aminohippuric acid clearance (CPAH), mean arterial blood pressure, and renal vascular resistance (RVR) 1 h before and 100 min after either oral gavage of 2 g bovine serum albumin or intravenous infusion of 5% glycine in female Sprague-Dawley rats previously fed for 3-8 wk a 0.5% or a 0.1% phosphorus diet. Baseline CIn, CPAH, blood pressure, and RVR were similar. After albumin gavage, CIn rose 20% (P < 0.01) for the 0.5% phosphorus group but did not change for rats fed the 0.1% phosphorus diet. Other measured parameters, including plasma glucagon and renin activity, were not influenced by dietary phosphorus content. In contrast, during intravenous infusion of glycine, hyperfiltration was induced in phosphorus-restricted rats. Thus dietary phosphorus restriction ablates oral protein but not intravenous amino acid-induced hyperfiltration, suggesting a gut-mediated mechanism for the former. These data highlight the potential importance of dietary phosphorus as a mediator of renal hemodynamics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Amino Acids / administration & dosage
  • Amino Acids / metabolism
  • Animals
  • Blood Pressure / physiology
  • Dietary Proteins / administration & dosage
  • Dietary Proteins / pharmacology*
  • Fasting
  • Female
  • Glucagon / blood
  • Glycine / administration & dosage
  • Hemodynamics / physiology
  • Homeostasis / physiology
  • Infusions, Intravenous
  • Injections, Intravenous
  • Inulin / metabolism
  • Kidney / blood supply
  • Kidney / drug effects
  • Kidney / physiology*
  • Phosphorus, Dietary / pharmacology*
  • Rats
  • Rats, Sprague-Dawley
  • Regional Blood Flow
  • Renin / blood
  • Vascular Resistance / physiology
  • p-Aminohippuric Acid / metabolism

Substances

  • Amino Acids
  • Dietary Proteins
  • Phosphorus, Dietary
  • Inulin
  • Glucagon
  • Renin
  • Glycine
  • p-Aminohippuric Acid