The angiotensin II receptor type 2 polymorphism influences haemodynamic function and circulating RAS mediators in normotensive humans.

BACKGROUND The haemodynamic responses to angiotensin II type 1 (AT1) receptor blockade may be mediated in part by interactions between angiotensin II and the angiotensin II type 2 receptor (AT2R). An AT2R G1675A gene polymorphism has been described, but the functional effects of this polymorphism are unknown. METHODS Haemodynamic function, circulating renin-angiotensin system mediators and norepinephrine were measured in young healthy subjects at baseline and at 2 and 4 weeks after treatment with irbesartan. Subjects were divided into two groups on the basis of the AT2R G1675A gene polymorphism: GG subjects (n = 12) and AA/GA subjects (n = 22). RESULTS AA/AG subjects exhibited hypotensive and renal vasodilatory responses to irbesartan at 4 weeks, but GG subjects did not. In accord with haemodynamic effects, circulating aldosterone levels were suppressed in AA/AG, while circulating norepinephrine levels were augmented only in GG subjects. In contrast, increases in circulating renin, angiotensin II and plasma renin activity after irbesartan were exaggerated in AA/AG subjects. CONCLUSIONS The AT2R G1675A polymorphism is a determinant of haemodynamic responses to AT1 receptor blockade, an effect that may be due to influences on aldosterone escape.