Gluconeogenesis, Cytosolic Redox Potential, and Phosphate and Fluid Transport in the Isolated Rabbit Proximal Tubule
Gluconeogenesis (GNG) in the kidney represents an important metabolic activity localized to the proximal tubules (1). It has been suggested that renal GNG may play a key role in the regulation of renal ammoniagenesis in metabolic acidosis (2) and also may contribute to blood glucose concentrations (3). However, it is not known whether renal GNG serves any functional role in solute and fluid transport in the proximal nephron. Recent observations from several laboratories suggested that GNG may play some role in the regulation of fluid and inorganic phosphate (Pi) reabsorption in the proximal tubule. For example, Dousa and associates proposed that cytosolic concentrations of the oxidized form of nicotinamide adenine dinucleotide (NAD+) may control proximal Pi reabsorption and as such GNG may modulate Pi transport through altering the cytosolic level of NAD+ (4). Silva and colleagues, who studied isolated perfused rat kidney, suggested that GNG and sodium reabsorption may compete for the common energy source, resulting in reciprocal changes in the rates of GNG and fluid reabsorption in the proximal tubules (5,6).
KeywordsHydrolysis Phosphorus Lactate Adenosine Pyruvate
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