ANGIOTENSIN-II RECEPTORS IN ENDOTHELIAL-CELLS

1. Angiotensin II (Ang II), the main effector of the renin-angiotensin system, exerts its vasoconstrictory and trophic actions on smooth mus cle cells via AT(1) receptors. However, Ang II does not act only on sm ooth muscle cells, as Ang II receptors are also present in endothelial cells. 2. The receptor type on these cells differs depending on the o rigin of the endothelium and the species. The rat endothelial receptor s are mostly of the AT(1) type, but AT(2) receptors have also been fou nd. The pharmacological characteristics of the AT(1) receptors on endo thelial cells are similar to those of other cell types. 3. Ang II stim ulates phospholipase C and phospholipase A(2) activation via the AT(1) receptor in endothelial cells. Ang II also stimulates the tyrosine ph osphorylation of several proteins in these cells. 4. Some studies sugg est that the AT(1) receptor mediates the release of vasodilator molecu les by endothelial cells and could modulate Ang II effect on smooth mu scle cells, Ang II may also inhibit endothelial cell growth via the AT (2) receptor. Finally, endothelial Ang II receptors may be implicated in the regulation of fibrinolysis. (C) 1997 Elsevier Science Inc.