Possible prorenin activating mechanisms in the blood vessel wall.

The blood-vessel wall has the potential for activating circulating prorenin by several mechanisms. Prorenin may be taken up by the blood vessel and activated by enzyme(s) localized on the vascular cells. We do not know whether this mechanism is usually operative or is only activated under certain conditions. This local activation system can increase the vascular-wall renin concentration and may be involved with the regulation of local vascular tone and regional blood flow. Circulating blood cells may release enzymes which can activate prorenin. At the inflammatory site, a neutrophil-dependent prorenin activating mechanism may be important for the increased production of angiotensin II which modulates vascular permeability and tone. In addition, at sites of vascular injury where platelets aggregate, prorenin may be activated locally and may play a role in the genesis of vasospasm.