The uteroplacental renin-angiotensin system

The components of the renin-angiotensin system (RAS) are expressed in the u teroplacental unit. The expression varies between species, probably due to the marked species differences in placental architecture. The conditions fo r angiotensin (Ang) IT formation exist and Ang II receptors are present thr oughout the human uteroplacental unit, indicating the presence of a functio nal local RAS. The uteroplacental RAS interacts with other regulatory syste ms and in this way modulates various aspects of tissue function. It is sugg ested that the uteroplacental RAS is important for the regeneration of the endometrium after shedding, and for decidualization, implantation and place ntation. The RAS participates in the regulation of the uteroplacental blood flow, prostaglandin synthesis and oestradiol secretion. Disturbances of th e uteroplacental RAS may lead to dysfunctional bleeding and to reduced uter oplacental blood flow in pregnancies complicated by pre-eclampsia and intra uterine growth retardation. (C) 2000 Harcourt Publishers Ltd.