An activated intrarenal reninangiotensin system (RAS) plays a crucial role in the pathogenesis of
hypertension and
chronic kidney diseases (CKD).
Angiotensinogen (AGT) is the only known substrate for
renin, which is the rate-limiting
enzyme of the RAS. Because the levels of AGT are close to the Michaelis-Menten constant for
renin, AGT levels can also control the RAS activity, and upregulation of AGT may lead to elevated
angiotensin peptide levels and increases in blood pressure. Recent studies on experimental animal models have documented the involvement of AGT in the intrarenal RAS activation and development of
hypertension. Enhanced intrarenal AGT
mRNA and/or
protein levels occur in experimental models of
hypertension and
kidney diseases supporting important roles in the development and progression of
hypertension and
kidney diseases. Urinary excretion rates of AGT provide a specific index of intrarenal RAS status in
angiotensin II-infused rats. Also, a direct quantitative method was recently developed to measure urinary AGT using human AGT ELISA. These data prompted us to measure urinary AGT in patients with
hypertension and CKD, and investigate correlations with clinical parameters. This brief review will address the potential of urinary AGT as a novel
biomarker of the intrarenal RAS status in
hypertension and CKD.