The tissue renin-angiotensin systems: focus on brain angiotensin, adrenal gland and arterial wall.

The enzyme renin has long been considered an exclusively renal enzyme responsible for the generation of angiotensin in the plasma, and angiotensin was considered a peptide hormone with specific target organs. Since renin has been discovered to occur not only in the kidney but in addition in a large number of other tissues, e.g. the salivary gland, the uterus, the blood vessels, the adrenal gland and the brain, this concept had to be revised. The possibility of local generation of angiotensin in these target tissues, where it has marked biological effects casts a new light on angiotensin as a more ubiquitous tissue factor or even a neurohormone.