Cerebral lactate uptake during exercise is driven by the increased arterial lactate concentration.

Exercise facilitates cerebral lactate uptake, likely by increasing arterial lactate concentration and hence the diffusion gradient across the blood-brain barrier. However, nonspecific β-adrenergic blockade by propranolol has previously reduced the arterio-jugular venous lactate difference (AV) during exercise, suggesting β-adrenergic control of cerebral lactate uptake. Alternatively, we hypothesized that propranolol reduces cerebral lactate uptake by decreasing arterial lactate concentration.

Similar hemostatic responses to hypovolemia induced by hemorrhage and lower body negative pressure reveal a hyperfibrinolytic subset of non-human primates.

Background: To study central hypovolemia in humans, lower body negative pressure (LBNP) is a recognized alternative to blood removal (HEM). While LBNP mimics the cardiovascular responses of HEM in baboons, similarities in hemostatic responses to LBNP and HEM remain unknown in this species.

Methods: Thirteen anesthetized baboons were exposed to progressive hypovolemia by HEM and, four weeks later, by LBNP.

Hemostatic responses to exercise, dehydration, and simulated bleeding in heat-stressed humans.

Heat stress followed by an accompanying hemorrhagic challenge may influence hemostasis. We tested the hypothesis that hemostatic responses would be increased by passive heat stress, as well as exercise-induced heat stress, each with accompanying central hypovolemia to simulate a hemorrhagic insult. In aim 1, subjects were exposed to passive heating or normothermic time control, each followed by progressive lower-body negative pressure (LBNP) to presyncope.

Hypoxia compounds exercise-induced free radical formation in humans; partitioning contributions from the cerebral and femoral circulation.

This study examined to what extent the human cerebral and femoral circulation contribute to free radical formation during basal and exercise-induced responses to hypoxia. Healthy participants (5♂, 5♀) were randomly assigned single-blinded to normoxic (21% O) and hypoxic (10% O) trials with measurements taken at rest and 30 min after cycling at 70% of maximal power output in hypoxia and equivalent relative and absolute intensities in normoxia. Blood was sampled from the brachial artery (a), internal jugular and femoral veins (v) for non-enzymatic antioxidants (HPLC), ascorbate radical (A, electron paramagnetic resonance spectroscopy), lipid hydroperoxides (LOOH) and low density lipoprotein (LDL) oxidation (spectrophotometry).