renal glucose absorption

Definition

Target type: biologicalprocess

A renal system process in which glucose is taken up from the collecting ducts and proximal and distal loops of the nephron. In non-mammalian species, absorption may occur in related structures. [GOC:yaf, PMID:11269503]

Renal glucose absorption is a vital process that ensures the body retains glucose, a crucial energy source, while preventing its loss in urine. It primarily occurs in the proximal convoluted tubule (PCT) of the nephron, the functional unit of the kidney. Here's a detailed breakdown:

1. **Filtration:** At the glomerulus, blood is filtered, and glucose, along with other small molecules, passes into the nephron's initial segment.

2. **Reabsorption in the PCT:** The PCT possesses a high density of sodium-glucose co-transporters (SGLT2 and SGLT1). These proteins actively transport glucose from the tubular fluid back into the bloodstream. This transport is driven by the sodium gradient established by the sodium-potassium pump.

3. **SGLT2 vs. SGLT1:** SGLT2 is primarily responsible for reabsorbing most of the filtered glucose (about 90%). It has a higher affinity for glucose than SGLT1 but is saturated at higher glucose concentrations. SGLT1, found in the later part of the PCT, reabsorbs the remaining glucose.

4. **Glucose Transport across the Basolateral Membrane:** Once inside the epithelial cells of the PCT, glucose moves across the basolateral membrane into the interstitial fluid and then into the peritubular capillaries. This movement is facilitated by GLUT2, a glucose transporter protein.

5. **Regulation:** Renal glucose reabsorption is tightly regulated by factors like blood glucose levels and insulin. When blood glucose rises, insulin stimulates glucose uptake by cells, reducing the amount of glucose delivered to the kidneys. This reduces the load on the SGLT transporters.

6. **Excretion:** Under normal circumstances, all filtered glucose is reabsorbed, resulting in virtually no glucose excretion in urine. However, in conditions like diabetes, where blood glucose levels are chronically elevated, the reabsorption capacity of the kidneys is overwhelmed, leading to glucose appearing in the urine (glucosuria).

This precise and efficient process of renal glucose reabsorption ensures that the body conserves a vital energy source while maintaining blood glucose homeostasis.'
"

Proteins (2)

Compounds (15)