The apelin receptor AGTRL1 is Gi/Go-coupled GPCRs expressed in the heart, coronary artery, aorta, internal mammary artery, pulmonary artery and saphenous vein, it also expressed in lung, kidney and adrenal gland. In AGTRL1 receptor knockout mice baseline blood pressure is not changed compared to wild-type animals. Vasoconstrictor responses to angiotensin II however are significantly more pronounced in the knockout animals.