The Regulator of G-Protein Signalling-1 (RGS1) controls G protein coupled receptor signalling by acting as a GTPase-activating protein for heterotrimeric G proteins. RGS1 has contrasting roles in haematopoietic and non-haematopoietic cells. We have previously shown that Rgs1 regulates macrophage accumulation in Angiotensin II (Ang II)-induced aortic aneurysms and Rgs1-/-ApoE-/- mice are protected from Ang II-induced aortic aneurysm rupture compared to ApoE-/- mice. Conversely, Ang II treatment increases systolic blood pressure to a greater extent in Rgs1-/-ApoE-/- mice than ApoE-/- mice and this is mediated by non-haematopoietic cells as indicated by bone marrow chimeras. However the precise role of RGS1 in hypertension and vascular-derived cells is unknown