Effects of angiotensin-(1-7) on forearm circulation in normotensive subjects and patients with essential hypertension.
Previous animal studies have shown that angiotensin (Ang)-(1-7) is a biologically active component of the renin-angiotensin system, acting as a vasoactive agent, and may play a role in the blood pressure regulation. There is little information, however, on the effect of Ang-(1-7) on human circulation or the mechanism of its action. To investigate the effect of Ang-(1-7) on forearm circulation and to determine whether this effect is altered in patients with essential hypertension, we measured change in forearm blood flow using venous occlusion plethysmography in response to intra-arterial infusion of Ang-(1-7) (10(-10), 10(-9), and 10(-8) mol/min; for 5 minutes) in normotensive control subjects (n=8) and patients with essential hypertension (n=8). Infusion of Ang-(1-7) significantly increased the forearm blood flow response in a dose-dependent manner in both normotensive control subjects (28.7+/-9.7%, at 10(-8) mol/min; P<0.05) and hypertensive patients (31.8+/-15.2%, at 10(-8) mol/min; P<0.05). The vasodilatory effect of Ang-(1-7) was similar in the two groups. Intra-arterial infusion of N(G)-monomethyl-L-arginine, a nitric oxide synthesis inhibitor, did not alter the forearm blood flow response to Ang-(1-7) in either group. These findings suggest that Ang-(1-7) causes vasodilation in forearm circulation of normotensive subjects and patients with essential hypertension through a pathway that is independent of nitric oxide synthesis.
Sasaki
S
S
First Department of Internal Medicine, Hiroshima University School of Medicine, Japan. sshota@mcai.med.hiroshima-u.ac.jp
Higashi
Y
Y
Nakagawa
K
K
Matsuura
H
H
Kajiyama
G
G
Oshima
T
T
D000704:Analysis of Variance; D000803:Angiotensin I / Q000494:pharmacology*; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001775:Blood Circulation / Q000187:drug effects*; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology*; D012039:Regional Blood Flow / Q000187:drug effects
D000959:Antihypertensive Agents; D010446:Peptide Fragments; D009569:Nitric Oxide; D000803:Angiotensin I; C118790:angiotensin I (1-7)