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This Article Full Text Full Text (PDF) All Versions of this Article: 586/14/3525    most recent jphysiol.2008.151555v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Van Guilder, G. P. Articles by DeSouza, C. A. PubMed PubMed Citation Articles by Van Guilder, G. P. Articles by DeSouza, C. A. Related Collections Cardiovascular

¹ Integrative Vascular Biology Laboratory, Department of Integrative Physiology, University of Colorado, Boulder, CO, USA
² Department of Medicine, University of Colorado at Denver, CO, USA
³ Denver Health Medical Center, Denver, CO, USA

We determined the effects of acute intra-arterial vitamin C administration and chronic oral vitamin C supplementation on the capacity of the endothelium to release t-PA in overweight and obese adults. Net endothelial t-PA release was determined in vivo in response to intrabrachial infusions of bradykinin and sodium nitroprusside in 33 sedentary adults: 10 normal-weight (BMI: 23.4 ± 0.5 kg m^–2; 7M/3F); and 23 overweight/obese (BMI: 31.2 ± 0.8 kg m^–2; 15M/8F). In 10 normal weight and eight overweight/obese adults the dose–response curves to bradykinin and sodium nitroprusside were repeated with a coinfusion of the antioxidant vitamin C (24 mg min^–1). Seventeen of the 23 overweight/obese adults completed a 3 month chronic oral vitamin C (500 mg day^–1) supplementation intervention. Intra-arterial administration of vitamin C significantly potentiated t-PA release in overweight/obese adults. Net release of t-PA was 95% higher (P < 0.01) after (from –0.9 ± 1.1 to 94.6 ± 16.2 ng (100 ml tissue)^–1 min^–1) compared with before (from –0.8 ± 0.8 to 49.9 ± 7.7 ng (100 ml tissue)^–1 min^–1) vitamin C administration. Daily vitamin C supplementation significantly increased t-PA release in overweight/obese adults (from 0.2 ± 0.9 to 48.2 ± 6.5 ng (100 ml tissue)^–1 min^–1) before supplementation versus (0.3 ± 0.5 to 66.3 ± 8.7 ng (100 ml tissue)^–1 min^–1) after supplementation. These results indicate that the antioxidant vitamin C favourably affects the capacity of the endothelium to release t-PA in overweight/obese adults. Daily vitamin C supplementation represents an effective lifestyle intervention strategy for improving endothelial fibrinolytic regulation in this at-risk population.

(Received 24 January 2008; accepted after revision 19 May 2008; first published online 22 May 2008)
Corresponding author C. DeSouza: Integrative Vascular Biology Laboratory, Department of Integrative Physiology, University of Colorado, 354 UCB, Boulder, CO 80309, USA. Email: desouzac{at}colorado.edu