Acute acidosis inhibits liver amino acid transport: no primary role for the urea cycle in acid-base balance
| Autor: | A. C. Schoolwerth, Louis Boon, Alfred J. Meijer, Wouter H. Lamers, P. J. E. Blommaart |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
medicine.medical_specialty
Alkalosis Physiology Metabolic alkalosis Acid–base homeostasis Hepatic Veins chemistry.chemical_compound Internal medicine medicine Animals Urea Amino Acids Rats Wistar Aorta Acidosis Acid-Base Equilibrium chemistry.chemical_classification Portal Vein Chemistry Biological Transport Metabolic acidosis Hydrogen-Ion Concentration medicine.disease Rats Amino acid Quaternary Ammonium Compounds Sodium Bicarbonate Endocrinology Liver Urea cycle Female Hydrochloric Acid medicine.symptom |
| Zdroj: | American Journal of Physiology-Renal Physiology. 267:F1015-F1020 |
| ISSN: | 1522-1466 1931-857X |
| DOI: | 10.1152/ajprenal.1994.267.6.f1015 |
| Popis: | To examine further the role of the liver in acid-base homeostasis, we studied hepatic amino acid uptake and urea synthesis in rats in vivo during acute acidosis and alkalosis, induced by infusion of 1.8 mmol of HCl or NaHCO3 over 3 h. Amino acids and NH4+ were measured in portal vein, hepatic vein, and aortic plasma, and arteriovenous differences of amino acids and urinary urea and NH4+ excretion were measured. In acidosis, urinary urea excretion was reduced 36% (P < 0.01), whereas urinary NH4+ excretion increased ninefold (P < 0.01), but the sum of urea and NH4+ excretion was unchanged. Total hepatic amino acid uptake, as determined from arteriovenous differences, was decreased by 63% (P < 0.01) in acidosis, with the major effect being noted with alanine and glycine. Only glutamine was released in both acidosis and alkalosis but was not significantly different in the two conditions. Since intracellular concentrations of readily transportable amino acids were not different at low pH despite accelerated protein degradation, these results indicate that hepatic amino acid transport was inhibited markedly and sufficiently to explain the observed decrease in urea synthesis. Total hepatic vein amino acid content was greater in acidosis than alkalosis (P < 0.01). Directly or indirectly, by conversion to glutamine elsewhere, these increased amino acids were degraded in kidney and accounted for the ninefold increase in urinary NH4+ excretion.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|