TY - JOUR
T1 - Valsartan improves the lower limit of cerebral autoregulation in rats
AU - Takada, Junichi
AU - Ibayashi, Setsuro
AU - Ooboshi, Hiroaki
AU - Ago, Tetsuro
AU - Ishikawa, Eiichi
AU - Kamouchi, Masahiro
AU - Kitazono, Takanari
AU - Iida, Mitsuo
PY - 2006/8
Y1 - 2006/8
N2 - The effects of angiotensin II type 1 receptor blockers (ARBs) on cerebral blood flow (CBF) autoregulation have not been fully clarified. Thus, we examined the acute effect of valsartan, the most selective ARB, on CBF autoregulation in spontaneously hypertensive rats. Intravenous administration of valsartan (0.3 mg/kg) reduced the mean arterial pressure (MAP) from 184±5 (mean±SEM) to 174±5 mmHg (p<0.001) without affecting CBF as measured by laser-Doppler flowmetry. The lower limit of CBF autoregulation (the MAP at which the CBF was 80% of the baseline value) in the valsartan-treated group (122±3 mmHg) was significantly lower than that in the control group (135±4 mmHg, p<0.05). Reverse transcribed-polymerase chain reaction and immunohistochemical staining demonstrated that both anglotensin II type 2 receptors and angiotensin II type 1 receptors (AT1Rs) were expressed in endothelial and smooth muscle cells of the rat cerebral arteries. These results suggest that specific inhibition of AT1Rs in the cerebral circulation causes the leftward shift of the lower limit of autoregulation.
AB - The effects of angiotensin II type 1 receptor blockers (ARBs) on cerebral blood flow (CBF) autoregulation have not been fully clarified. Thus, we examined the acute effect of valsartan, the most selective ARB, on CBF autoregulation in spontaneously hypertensive rats. Intravenous administration of valsartan (0.3 mg/kg) reduced the mean arterial pressure (MAP) from 184±5 (mean±SEM) to 174±5 mmHg (p<0.001) without affecting CBF as measured by laser-Doppler flowmetry. The lower limit of CBF autoregulation (the MAP at which the CBF was 80% of the baseline value) in the valsartan-treated group (122±3 mmHg) was significantly lower than that in the control group (135±4 mmHg, p<0.05). Reverse transcribed-polymerase chain reaction and immunohistochemical staining demonstrated that both anglotensin II type 2 receptors and angiotensin II type 1 receptors (AT1Rs) were expressed in endothelial and smooth muscle cells of the rat cerebral arteries. These results suggest that specific inhibition of AT1Rs in the cerebral circulation causes the leftward shift of the lower limit of autoregulation.
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U2 - 10.1291/hypres.29.621
DO - 10.1291/hypres.29.621
M3 - Article
C2 - 17137218
AN - SCOPUS:33748950839
SN - 0916-9636
VL - 29
SP - 621
EP - 626
JO - Hypertension Research
JF - Hypertension Research
IS - 8
ER -