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


CONCLUSIONS
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.
On
Young Keun
YK
Division of Cardiology, Department of Internal Medicine, Soonchunhyang University Medical College, 657 Hanam-dong, Yongsan-gu, Seoul 140-743, Korea.
Kim
Cheol Ho
CH
Sohn
Dae Won
DW
Oh
Byung Hee
BH
Lee
Myoung Mook
MM
Park
Young Bae
YB
Choi
Yun Shik
YS
D000328:Adult; D000368:Aged; D017311:Amlodipine / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000627:therapeutic use; D001205:Ascorbic Acid / Q000627:therapeutic use*; D002121:Calcium Channel Blockers / Q000627:therapeutic use; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D014664:Vasodilation / Q000187:drug effects; D019323:omega-N-Methylarginine / Q000494:pharmacology
D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D017311:Amlodipine; D019323:omega-N-Methylarginine; D019001:Nitric Oxide Synthase; D001205:Ascorbic Acid