Metabolism in Kidney Disease

The kidney contains numerous types of cells; this cellular heterogeneity and functional diversity make the kidney an organ with great metabolic activity. Most solute reabsorption occurs in the proximal tubules, so much energy is used to recover them. The proximal tubules use fatty acid oxidation as their preferred metabolic pathway to carry out this process. The kidney plays a central role in glucose reabsorption, production, and utilization. However, it is important to note that the proximal tubules of the nephron prefer fatty acids as energy. Much of the glucose in the glomerular filtrate is reabsorbed in the proximal tubules by the two isoforms of glucose/Na+ transporters (SGLT1 and SGLT2) located in the apical zone of the tubular epithelium. It is well known that the human kidney is a key organ for maintaining systemic glucose homeostasis through gluconeogenesis. The only organs that can synthesize and release glucose into the bloodstream are the kidney and the liver because both synthesize glucose 6-phosphatase, which is necessary to form glucose from glucose-6-phosphate. Remarkably, the kidney produces approximately 25% of all glucose delivered into the blood. Several studies have demonstrated that lactate is the primary substrate of gluconeogenesis in the kidney. However, after kidney injury, metabolism is impaired, resulting in increased lactic acid generation and decreased fatty acid oxidation.

Keywords: Amino acid metabolism, Fatty acid oxidation, Gluconeogenesis, Glycolysis, Metabolic activity.