ABSTRACT
The RAAS is an enzyme cascade that
Figure 7.1 details the principal steps in the
cascade and indicates the points at which it
can be inhibited. Angiotensin II has long been
known to mediate vasoconstriction, promote
sodium retention and stimulate aldosterone
release. Aldosterone may also be considered an
effector hormone of the RAAS.2 Angiotensin
II promotes sodium and water retention and
is crucial in the regulation of peripheral
resistance. It has been shown to promote the
proliferation of a variety of cell types,
including vascular smooth muscle cells,
fibroblasts and mesangial cells, and to
stimulate the deposition of extracellular
matrix in a number of tissues, including the
heart.3-5 These effects are frequently mediated
in a paracrine fashion through the action of a
The components of the RAAS are found in
tissues as well as the circulation. However, the
relative importance of the systemic and tissue
systems is not yet clear.