Effects of acute methionine loading and vitamin C on endogenous fibrinolysis, endothelium-dependent vasomotion and platelet aggregation

C. Labinjoh, D. E. Newby*, I. B. Wilkinson, I. L. Megson, H. MacCallum, V. Melville, N. A. Boon, D. J. Webb

*Corresponding author for this work

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

We assessed forearm blood flow and plasma fibrinolytic factors in eight healthy males who received unilateral brachial artery infusions of the endothelium-dependent vasodilator, substance P, and the endothelium-independent vasodilator, sodium nitroprusside. These measurements, together with platelet aggregation studies, were performed on four occasions after double-blind randomized ingestion of placebo, methionine (0.1 mg/kg), vitamin C (2 g) and methionine plus vitamin C. Blood flow and platelet aggregation responses were unaffected by methionine loading. Substance P caused dose-dependent increases in plasma tissue plasminogen activator (t-PA) antigen (from 3.0 ± 0.1 to 4.7 ± 0.4 ng/ml; P < 0.001) and activity (from 1.2 ± 0.2 to 4.2 ± 0.4 i.u./ml; P < 0.001), which were augmented during acute methionine loading (4.7 ± 0.4 to 5.6 ± 0.5 ng/ml and 4.2 ± 0.4 to 5.5 ± 0.9 i.u./ml respectively; P ≤ 0.05). Moreover, the estimated net release of t-PA was enhanced during methionine loading (two-way ANOVA; P = 0.02), but this was unaffected by vitamin C supplementation. We conclude that, in the absence of alterations in endothelium-dependent vasomotion or platelet aggregation, substance P-induced t-PA release is enhanced following methionine loading. This suggests that the acute endogenous fibrinolytic capacity is augmented during acute hyperhomocysteinaemia in healthy humans via an oxidation-independent mechanism.

Original languageEnglish
Pages (from-to)127-135
Number of pages9
JournalClinical Science
Volume100
Issue number2
DOIs
Publication statusPublished - 2001
Externally publishedYes

Keywords

  • Blood flow
  • Endothelium
  • Hyperhomocysteinaemia
  • Plasminogen activators
  • Platelet aggregation

Fingerprint Dive into the research topics of 'Effects of acute methionine loading and vitamin C on endogenous fibrinolysis, endothelium-dependent vasomotion and platelet aggregation'. Together they form a unique fingerprint.

  • Cite this

    Labinjoh, C., Newby, D. E., Wilkinson, I. B., Megson, I. L., MacCallum, H., Melville, V., ... Webb, D. J. (2001). Effects of acute methionine loading and vitamin C on endogenous fibrinolysis, endothelium-dependent vasomotion and platelet aggregation. Clinical Science, 100(2), 127-135. https://doi.org/10.1042/CS20000178