Afferent arteriole (AA)

The afferent arteriole is a specialized resistance vessel in the kidney that delivers blood to the glomerular capillaries for filtration (StatPearls, 2023). It plays a central role in maintaining a stable glomerular filtration rate (GFR) through autoregulatory mechanisms, including the myogenic response and tubuloglomerular feedback (TGF) (NIH, 2022). In the TGF mechanism, the macula densa senses distal sodium delivery and modulates afferent tone via adenosine-mediated vasoconstriction or nitric oxide-mediated vasodilation. Pathologically, the afferent arteriole is a primary site of damage in hypertension, where it undergoes hyaline thickening, and in diabetes, where inappropriate vasodilation leads to glomerular hyperfiltration (Wikipedia, 2024). Therapeutic agents such as SGLT2 inhibitors (e.g., dapagliflozin) target these physiological pathways to induce afferent vasoconstriction, thereby reducing intraglomerular pressure and providing renoprotection (PubMed, 2021). Conversely, the use of NSAIDs can lead to acute kidney injury by inhibiting the production of vasodilatory prostaglandins necessary to maintain afferent blood flow during states of low systemic perfusion (StatPearls, 2023).

Other names

Arteriola glomerularis afferensAfferent glomerular arteriole

Regulation of vascular tone through prostaglandin-mediated vasodilation (inhibited by NSAIDs), tubuloglomerular feedback-mediated vasoconstriction (activated by SGLT2 inhibitors), and L-type calcium channel-mediated contraction (blocked by CCBs).