Tissue renin angiotensin systems

The renin-angiotensin-aldosterone system (RAAS) is a well-established regulator of intravascular volume and blood pressure. An increasing body of evidence indicates that various components of the renin-angiotensin system (RAS) are either differentially taken up into tissues from the circulation or independently synthesized in tissues, with the result that the tissue concentrations of the effector hormone angiotensin can be locally determined. Evidence also has been developed that renin and prorenin can function in a hormone-like fashion, binding to specific receptors and generating second-messenger cascades. Finally, the components of the RAS seem to be capable of functioning in an intracellular, or intracrine, mode. Collectively, these observations suggest an expanded view of the role of the RAAS in health and disease, and point to an important role for tissue RASs.