Angiotensinogen is the precursor of angiotensin and is cleaved into angiotensin I and II in the renin-angiotensin system, and it has long been reported to play an important role in controlling blood pressure. In recent years interest related to the role of the renin-angiotensin system in arterial pressure control and the pathophysiology of hypertension has been shifting to its local role in various tissues. Among the studies urinary excretion of angiotensinogen in a rat model of angiotensin II (AII)-dependent hypertension has been reported to be a marker of the activity of the local intrarenal renin-angiotensin system. Intrarenal AII increases to an extent in AII-dependent hypertension that cannot be explained by the plasma AII equilibration alone, and two mechanisms, an increase in intracellular uptake of AII and an increase in intrarenal expression of angiotensinogen, have been proposed to explain it.