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Clinical Trial
. 2002 Jun;17(2):131-7.
doi: 10.3904/kjim.2002.17.2.131.

Improvement of endothelial function by amlodipine and vitamin C in essential hypertension

Young Keun On  1 , Cheol Ho Kim, Dae Won Sohn, Byung Hee Oh, Myoung Mook Lee, Young Bae Park, Yun Shik Choi
Affiliations
Clinical Trial

Improvement of endothelial function by amlodipine and vitamin C in essential hypertension

Young Keun On et al. Korean J Intern Med. 2002 Jun.

Abstract

Background: The effects of antihypertensive agents on endothelial function have not been fully evaluated in human hypertension and data on the forearm circulation of humans are controversial. The aim of this study was (1) to evaluate the endothelial function in hypertensive patients (2) to investigate whether vitamin C administration has any benefit on the endothelial function and (3) to determine whether treatment with calcium antagonist improves endothelial dysfunction in hypertensive patients.

Methods: The endothelial function was estimated using venous occlusion plethysmography (VOP) in 8 hypertensive patients and 8 healthy volunteers. The patients in the hypertension group were treated with amlodipine, then examined again. The change of forearm blood flow (FBF) was measured with acetylcholine infusion through brachial artery and also with intra-arterial vitamin C.

Results: Forearm blood flow response to acetylcholine was significantly enhanced with intra-arterial infusion of vitamin C in hypertensive group before antihypertensive treatment. Co-infusion of L-NMMA, an inhibitor of nitric oxide synthase, blunted forearm blood flow response to acetylcholine. After treatment with amlodipine for 2 months in hypertensive group, endothelium-dependent vasorelaxation to acetylcholine was significantly improved compared to pretreatment, and vitamin C did not affect the improved endothelial function by amlodipine treatment.

Conclusion: Vitamin C (acutely) and amlodipine (chronically) improved endothelial function in hypertensive patients. These results suggest that increased oxidative stress, at least in part, may be involved in the decreased endothelial function in hypertension.

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Figures

Figure 1.
Figure 1.
Methods; venous occlusion plethysmography Acetylcholine was infused intra-arterially at 7.5, 15 and 30 g/min for 5 minutes for each dose level and forearm blood flow was measured during the last 2 minutes of each dose. Forearm blood flow response to acetylcholine was assessed during the infusion of dextrose solution (stage 1), intra-arterial infusion of vitamin C (stage 2) and intra-arterial co-infusion of vitamin C and L-NMMA (NG-monomethyl-L-arginine (stage 3).
Figure 2.
Figure 2.
FBF responses to three doses of acetylcholine in normal control and hypertensive patients. Values are mean±SEM. Ach1, Ach2 and Ach3 represent 7.5, 15 and 30 μg/min, respectively.
Figure 3.
Figure 3.
Effect of vitamin C and NMMA on the FBF response to acetylcholine.
Figure 4.
Figure 4.
Effect of amlodipine treatment on the vasodilatory response to acetylcholine (A). Intra-arterial infusion of vitamin C in amlodipine treated hypertensive group did not change the forearm blood flow response to acetylcholine (B). Co-infusion of L-NMMA, an inhibitor of nitric oxide synthase, blunted forearm blood flow response to acetylcholine (C).
See this image and copyright information in PMC

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