title: Ascorbic acid prevents vascular dysfunction induced by oral glucose load in healthy subjects.
abstract: OBJECTIVE
  To examine the effects of oral glucose load on forearm circulatory regulation before and after ascorbic acid administration in healthy subjects.
  
  
  METHODS
  Microcirculation study with laser Doppler was performed at the hand in basal conditions, after ischemia and after acetylcholine and nitroprusside; strain gauge plethysmography was performed at basal and after ischemia. The tests were repeated in the same sequence 2 hour after oral administration of glucose (75 g). The subjects were randomised for administration of ascorbic acid (1 g bid) or placebo (sodium bicarbonate 1 g bid) for 10 days. After that, the tests were repeated before and after a new oral glucose load. Blood pressure and heart rate were monitored.
  
  
  RESULTS
  Macrocirculatory flux, pressure values and heart rate were unvaried throughout the study. The glucose load caused a reduction in the hyperemic peak flow with laser Doppler and plethysmography; it reduced flux recovery time and hyperemic curve area after ischemia; acetylcholine elicited a minor increase in flux with laser Doppler. The response to nitroprusside was unvaried after glucose load as compared to basal conditions. Treatment with ascorbic acid prevented the decrease in hyperemia after glucose, detected with laser Doppler and plethysmography. Ascorbic acid prevented the decreased response to acetylcholine after glucose, the response to nitroprusside was unaffected by ascorbic acid. Results after placebo were unvaried.
  
  
  CONCLUSIONS
  Oral glucose load impairs endothelium dependent dilation and hyperaemia at microcirculation, probably via oxidative stress; ascorbic acid can prevent it.
authors.affiliation: Division of Vascular Rehabilitation, University of Verona, Policlinico Hospital, Verona, Italy. sergio.demarchi@univr.it
authors.forename: Sergio
authors.initials: S
authors.lastname: De Marchi
authors.forename: Manlio
authors.initials: M
authors.lastname: Prior
authors.forename: Anna
authors.initials: A
authors.lastname: Rigoni
authors.forename: Sara
authors.initials: S
authors.lastname: Zecchetto
authors.forename: Fanny
authors.initials: F
authors.lastname: Rulfo
authors.forename: Enrico
authors.initials: E
authors.lastname: Arosio
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000975:Antioxidants / Q000627:therapeutic use*; D001205:Ascorbic Acid / Q000627:therapeutic use*; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology*; D005260:Female; D005947:Glucose / Q000008:administration & dosage / Q000009:adverse effects*; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000187:drug effects* / Q000502:physiology*
chemical_list: D000975:Antioxidants; D005947:Glucose; D001205:Ascorbic Acid