Absorption of glucose by kidney is by:
**Core Concept**
The absorption of glucose by the kidney is a critical process that involves the reabsorption of glucose from the filtrate back into the bloodstream. This process is mediated by specific transport proteins in the renal tubules, particularly in the proximal convoluted tubule (PCT). The main glucose transporter responsible for this process is SGLT2 (sodium-glucose cotransporter 2).
**Why the Correct Answer is Right**
Glucose reabsorption in the PCT occurs through a sodium-dependent mechanism. SGLT2 is a high-capacity, low-affinity transporter that binds to both sodium ions and glucose molecules. This binding causes a conformational change in the transporter, which then undergoes a series of ATP-driven steps to transport both sodium and glucose into the renal tubular cells. This process is essential for maintaining glucose homeostasis in the body.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not applicable to glucose reabsorption in the kidney.
**Option B:** This option is incorrect because the primary glucose transporter in the kidney is SGLT2, not SGLT1.
**Option C:** This option is incorrect because glucose reabsorption in the kidney is not mediated by the same mechanism as glucose absorption in the intestine.
**Clinical Pearl / High-Yield Fact**
It is essential to note that individuals with SGLT2 mutations or inhibitors (such as those used in the treatment of diabetes) may experience glucose loss in the urine, leading to glycosuria.
**Correct Answer: C. SGLT2**