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Postprandial hyperglycemia (PPH) impairs vascular endothelial function (VEF). A single bout of aerobic exercise (AE) attenuates PPH-induced decreases in brachial artery flow-mediated dilation (FMD), a non-invasive measure of VEF, in healthy adults for up to 17 h post-exercise. Studies examining the effects of resistance exercise (RE) on postprandial FMD responses are lacking. We hypothesized that a single bout of exercise performed the prior evening would attenuate PPH-induced decreases in FMD, independent of exercise modality. In a randomized, cross-over design, overweight/obese adults [n = 11 (8 women); 22 ± 4 years; 32.3 ± 5.8 kg m−2] completed 3 separate trials: control (seated rest), AE (30 min at ~ 60% VO2max), or whole-body RE (30 min, 6 exercises, 3 × 10-repetition maximum). Each trial occurred 14–17 h prior to an oral glucose tolerance test (OGTT). Brachial artery FMD and plasma glucose and insulin were measured prior to and at 30-min intervals for 2 h following the OGTT. Repeated-measures ANOVA and Bonferroni post hoc tests were used to evaluate differences within and between trials. Trials occurred 15.3 ± 1.0 h prior to the OGTT. Relative to baseline, FMD transiently decreased (P

Background Whey protein is a potential source of bioactive peptides. Based on findings from in vitro experiments indicating a novel whey derived peptide (NOP-47) increased endothelial nitric oxide synthesis, we tested its effects on vascular function in humans. Methods A randomized, placebo-controlled, crossover study design was used. Healthy men (n = 10) and women (n = 10) (25 ± 5 y, BMI = 24.3 ± 2.3 kg/m2) participated in two vascular testing days each preceded by 2 wk of supplementation with a single dose of 5 g/day of a novel whey-derived peptide (NOP-47) or placebo. There was a 2 wk washout period between trials. After 2 wk of supplementation, vascular function in the forearm and circulating oxidative stress and inflammatory related biomarkers were measured serially for 2 h after ingestion of 5 g of NOP-47 or placebo. Macrovascular and microvascular function were assessed using brachial artery flow mediated dilation (FMD) and venous occlusion strain gauge plethysmography. Results Baseline peak FMD was not different for Placebo (7.7%) and NOP-47 (7.8%). Placebo had no effect on FMD at 30, 60, and 90 min post-ingestion (7.5%, 7.2%, and 7.6%, respectively) whereas NOP-47 significantly improved FMD responses at these respective postprandial time points compared to baseline (8.9%, 9.9%, and 9.0%; P < 0.0001 for time × trial interaction). Baseline reactive hyperemia forearm blood flow was not different for placebo (27.2 ± 7.2%/min) and NOP-47 (27.3 ± 7.6%/min). Hyperemia blood flow measured 120 min post-ingestion (27.2 ± 7.8%/min) was unaffected by placebo whereas NOP-47 significantly increased hyperemia compared to baseline (29.9 ± 7.8%/min; P = 0.008 for time × trial interaction). Plasma myeloperoxidase was increased transiently by both NOP-47 and placebo, but there were no changes in markers inflammation. Plasma total nitrites/nitrates significantly decreased over the 2 hr post-ingestion period and were lower at 120 min after placebo (-25%) compared to NOP-47 (-18%). Conclusion These findings indicate that supplementation with a novel whey-derived peptide in healthy individuals improves vascular function.

Exposure of cells of the K-562 erythroleukemia cell line to 4-hydroperoxycyclophosphamide (4-HC), an analog of activated cyclophosphamide, causes a concentration-dependent inhibition of in vitro colony formation by these cells. For investigation of the role of glutathione (GSH) in the metabolism of 4-HC, GSH levels of K-562 cells were modulated by exposing the cells to buthionine sulfoximine (BSO), a specific inhibitor of GSH synthesis, and/or to GSH ethyl esters. Both the mono- and diethyl esters of GSH were synthesized in our laboratories and their identities were determined by chromatographic methods and fast-atom-bombardment mass spectrometry. An HPLC method including electrochemical detection used for thiol determination was applied for the measurement of GSH esters. Incubation of the cells with BSO depleted GSH levels to approximately 11% of control values and potentiated the cytotoxicity of 4-HC. By contrast, exposure to GSH esters approximately doubled GSH levels and protected the cells against the toxicity of 4-HC. Moreover, when cellular GSH levels were first depleted by BSO exposure and then replenished by incubation with GSH esters, the BSO-associated potentiation of 4-HC cytotoxicity was abolished. The work described herein extends the application of an HPLC method used for thiol determination to the measurement of GSH ethyl esters. In addition, it established that GSH acts as a competitive protecting agent against the in vitro toxicity of 4-HC in the K-562 cell line.