Metabolism in the domestic fowl (Gallus domesticus) : hepatic and renal concentrations of metabolites, and measurements of metabolite concentrations in abdominal blood vessels supplying and draining leg, liver and kidney

Tinker, Donald Andrew (1984) Metabolism in the domestic fowl (Gallus domesticus) : hepatic and renal concentrations of metabolites, and measurements of metabolite concentrations in abdominal blood vessels supplying and draining leg, liver and kidney. Doctoral (PhD) thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (37MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

Physiological levels of blood gases can be maintained in an anesthetized, abdominally opened fowl by means of a simple unidirectional ventilation technique. Hepatic ATP levels and ATP/ADP ratios in control birds measured using this ventilation technique have been found to be high (1.9 micromole/g and 1.4 respectively) and are comparable to those reported in rats. Hepatic lactate levels and the lactate:pyruvate ratio were lower than is reported for non-ventilated chickens. Elevations of the tissue concentration of AMP, fructose-1,6-bisphosphate and inorganic phosphate and fall in ATP, in ischemic liver are consistent with an activation of glycogen phosphorylase, phosphofructokinase and pyruvate kinase - all indicative of the increased glycolytic flux in ischemic chicken liver. -- A six-day fast in chickens results in a 55% drop in hepatic glucose, an increase in the measures of cellular energy level in the liver, and a shift to a more oxidized hepatic cytosolic NAD⁺/NADH ratio. In contrast, glucose levels, cellular energy level indices and the redox state of the kidney cytosolic NADH system remain unchanged after a six-day fast. It is concluded that the relative availability of cytosolic reducing equivalents results in the process of gluconeogenesis from amino acids and pyruvate being more favored in the kidney of a fasted chicken than in its liver. -- Measurements of afferent-efferent differences across liver in the fed and fasted states suggest a significant uptake of glucose and lactate and most amino acids. A negative afferent-efferent difference for urate across liver in the fasted, and not in the fed state, indicates that deamination of amino acids is more prevalent in the fasted liver. -- Measurements of arteriovenous differences across muscle indicate that this tissue releases amino acids into the circulation in the fasted state and takes up no glucose. In the fed state no amino acids are released by muscle, although glucose is taken up. -- In the fed state there is no significant afferent-efferent difference across kidney for glucose. Measurements of afferent-efferent differences across kidney suggest that in the fasted state there is a significant release of glucose and an uptake of amino acids, urate, and lactate. If the renal portal component of total renal blood flow is assumed to be greater than 30% then when the sum is calculated of the gluconeogenic amino acids for which there is a significant uptake across kidney, the value (in glucose equivalents), is equal to the figure for the release of glucose. It is concluded that the kidney is a major gluconeogenic organ in the fasted chicken.

Actions (login required)

View Item