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In humans, circulating blood cells such as platelets are being increasingly used as a readily available and minimally invasive biospecimen to determine mitochondrial respiratory function. Here, we set out to determine the influence of sample preparation, assay buffer composition, and instrumental platform, on the respiratory function of platelets isolated from human blood.Approximately 50 mL of whole blood was collected from healthy adults (n=16) following an overnight (>12 hr.) fast. Platelets were immediately isolated from whole blood by centrifugation. Respiratory function was assayed in intact and permeabilized platelets using an Oxygraph-2K (O2K) high-resolution respirometer (Oroboros Instruments). Respiratory function was assayed in intact platelets suspended in either culture (RPMI) or respiration (MIR05) media (both supplemented with 5 mM glucose, 1 mM pyruvate and 2 mM glutamine), or the participants own plasma. Respiratory function was also assayed in digitonin-permeabilized platelets suspended in both RPMI and MIR05. In addition, respiratory function was determined in intact platelets using a Seahorse Extra-Cellular Flux analyzer (XFe) in RPMI buffer containing 5 mM glucose, 1 mM pyruvate and 2 mM glutamine.In intact platelets assayed in suspension using an O2K, routine and ATP-linked respiration were 35 and 34% greater in cells assayed in RPMI compared to MIR05, respectively (P Supported by USDA-ARS Project 6026-51000-012-06S, NIH 5P20GM109096-07 and 5R35GM142744-02. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Although evidence demonstrates the fundamental role of shear stress in vascular health, predominantly through the release of nitric oxide (NO), the mechanisms by which endothelial cells (EC)s sense and transduce shear are poorly understood. In cultured ECs tyrosine phosphorylation of PECAM-1 has been shown to activate eNOS in response to shear stress. However, in the human skeletal muscle microcirculation PECAM-1 was not activated in response to exercise or passive leg movement. Given this contradiction, this study aimed to assess the effect of exercise on conduit artery PECAM-1 and eNOS activation in humans. Eleven males were randomised to two groups; 30 min of handgrip exercise (

Background: Cocoa flavanols (CF) may exert health benefits through their potent vasodilatory effects which are perpetuated by elevations in nitric oxide (NO) bioavailability. These vasodilatory effects may contribute to improved delivery of blood and oxygen to exercising muscle.Objective: Therefore, the objective of this study was to examine how CF supplementation impacts pulmonary oxygen uptake (V̇O2) kinetics and exercise tolerance in sedentary middle-aged adults.Methods: We employed a double-blind cross-over, placebo-controlled design whereby 17 participants (11 male, 6 female; mean±SD, 45±6 years) randomly received either 7 days of daily CF (400 mg) or placebo (PL) supplementation. On day 7, participants completed a series of ‘step’ moderate- and severe-intensity exercise tests for the determination of oxygen uptake kinetics.Results: During moderate-intensity exercise, the time constant of the fundamental phase of V̇O2 kinetics (τV̇O2) was decreased by 15% in CF as compared to PL (mean±SD; PL: 40±12 vs. CF: 34±9 s, P=0.019), with no differences in the amplitude of V̇O2 (AV̇O2; PL: 0.77±0.32 vs. CF: 0.79±0.34 l min−1, P=0.263). However, during severe-intensity exercise, τV̇O2,the amplitude of the slow component (SCV̇O2) and exercise tolerance (PL: 435±58 vs. CF: 424±47 s, P=0.480) were unchanged between conditions.Conclusions: Our data show that acute CF supplementation enhanced oxygen uptake kinetics during moderate-, but not severe-intensity exercise in middle-aged participants. These novel effects of CFs, in this demographic, may contribute to improved tolerance of moderate-activity physical activities, which appear commonly present in daily life.Registered under ClinicalTrials.gov Identifier no. NCT04370353

Effort axillary-subclavian vein thrombosis in young patients has produced long-term disability because of the failure of the thrombosed vein to recanalize. Ten consecutive patients treated in our institution were analyzed. All patients were diagnosed by venography. Four patients received thrombolytic therapy. Three of these had complete resolution and one had partial resolution of the symptoms and thrombus, that was confirmed by venography and duplex imaging. The remaining six patients were treated with conventional anticoagulant therapy. Three of these patients had no resolution, one had complete resolution of both symptoms and thrombus, and two had only partial resolution of symptoms but no resolution of thrombus. Thrombolytic therapy appears to be superior to anticoagulation in the dissolution of symptoms in effort vein thrombosis and should be considered in its management if the diagnosis is made early.