Effect of angiotensin II on pulse wave velocity in humans is mediated through angiotensin II type 1 (AT(1)) receptors.
The objective of this study was to examine the effect of angiotensin II (Ang II) and angiotensin II type 1 (AT(1)) receptor blockade on pulse wave velocity (PWV) in healthy humans. We studied nine young male volunteers in a double-blind randomised crossover design. Carotid-femoral PWV (an index of arterial stiffness) was measured by using a Complior machine. Subjects were previously treated for 3 days with once-daily dose of either a placebo or valsartan 80 mg. On the third day, they were infused with either placebo or 5 ng/kg/min of Ang II over 30 min. Subjects thus received placebo capsule + placebo infusion (P), valsartan + placebo infusion (V), placebo + Ang II infusion (A), and valsartan + Ang II infusion (VA) combinations. Heart rate (HR), blood pressure and PWV were recorded at baseline and then every 10 min during infusion and once after the end of infusion. There were significant increases in systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) with A compared with P (P = 0.002, P = 0.002, P = 0.001 respectively). These rises in blood pressure were completely blocked by valsartan. A significant rise in PWV by A was seen compared with P (8.38 +/- 0.24 vs 7.48 +/- 0.24 m/sec, P = 0.013) and was completely blocked by valsartan; VA compared with P (7.27 +/- 0.24 vs 7.48 +/- 0.24 m/sec, P = NS). Multiple linear regression analysis showed that blockade of Ang II induced increase in blood pressure by valsartan contributed to only 30% of the total reduction in Ang II induced rise in PWV (R(2) = 0.306). The conclusions were that valsartan completely blocks the effect of Ang II on PWV. The effect of Ang II on PWV is mediated through AT(1)receptors. Reduction in PWV by Ang II antagonist is not fully explained by its pressure lowering effect of Ang II and may be partially independent of its effect on blood pressure.
Rehman
A
A
Department of Pharmacology, School of Medical Science, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan. rhadeeja@tm.net.my
Rahman
A R A
AR
Rasool
A H G
AH
D000328:Adult; D000804:Angiotensin II / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001783:Blood Flow Velocity / Q000187:drug effects*; D002339:Carotid Arteries / Q000187:drug effects; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005263:Femoral Artery / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D011674:Pulse; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000187:drug effects*; D012016:Reference Values; D013777:Tetrazoles / Q000494:pharmacology*; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology*; D000068756:Valsartan; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D057911:Angiotensin Receptor Antagonists; D000959:Antihypertensive Agents; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D013777:Tetrazoles; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D000068756:Valsartan; D014633:Valine