Effect of ascorbic acid on forearm reactive hyperaemia in patients with hypercholesterolaemia.
BACKGROUND
This study was designed to research the effect of hypercholesterolaemia and ascorbic acid on forearm blood flow (FBF) reactive hyperaemia (RH). Reactive hyperaemia seems to be at least partly endothelium-dependent. Endothelial dysfunction has been described in patients with hypercholesterolaemia, and has been reversed with ascorbic acid administration.


METHODS
Forearm blood flow was studied with venous occlusion plethsmography in 26 healthy volunteers and 46 hypercholesterolaemic patients. Hypercholesterolaemic patients were divided into two groups. Group A comprised 25 patients, who received ascorbic acid and group B comprised 21 patients, who received placebo. All subjects underwent measurement of FBF at baseline and during RH (phase A). Forearm blood flow during RH was measured every 15 seconds for three minutes. Subsequently patients in group A received 2 g of ascorbic acid orally in the form of effervescent tablets, and patients in group B received placebo orally in the same form. Forearm blood flow measurements at baseline and during RH were repeated two hours later (phase B).


RESULTS
Maximal percent increase of FBF was significantly higher in healthy subjects than in hypercholesterolaemic patients (139.1+/-12.1% versus 73.1+/-11.0% respectively, P<0.05). Duration of RH was smaller in hypercholesterolaemic patients compared to normal subjects (60.9+/-17.1 seconds versus 105.6+/-10.2 seconds, P<0.05). Administration of ascorbic acid but not of placebo increased the duration of RH (69.1+/-11.1 seconds versus 104.1+/-12.2 seconds, P<0.05) but not of peak RH FBF.


CONCLUSIONS
Hypercholesterolaemia seems to impair both the early and late phase of RH. Ascorbic acid improves only the duration of RH, possibly due to its antioxidant effect on endothelium.
Protogerou
Athanassios D
AD
Department of Clinical Therapeutics, Alexandra University Hospital, Athens, Greece. athanprot@oneway.gr
Lekakis
John P
JP
Kontoyanni
Dimitra D
DD
Stamatelopoulos
Kimon S
KS
Tsotsoros
Nikos D
ND
Papaioannou
Theodoros G
TG
Tryfonopoulos
Dimitrios J
DJ
Papamichael
Christos M
CM
Stamatelopoulos
Stamatios F
SF
D000328:Adult; D000368:Aged; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D006937:Hypercholesterolemia / Q000150:complications / Q000503:physiopathology*; D006940:Hyperemia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010991:Plethysmography; D012039:Regional Blood Flow / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
D000975:Antioxidants; D001205:Ascorbic Acid