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

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Exercise facilitates cerebral lactate uptake, likely by increasing arterial lactate concentration and hence the diffusion gradient across the blood brain barrier. However, non-specific β-adrenergic blockade by propranolol has previously reduced the arterio-jugular venous lactate difference (AVLac) during exercise, suggesting β-adrenergic control of cerebral lactate uptake. Alternatively, we hypothesize that propranolol reduces cerebral lactate uptake by decreasing arterial lactate concentration. To test that hypothesis, we evaluated cerebral lactate uptake taking changes in arterial concentration into account. Nine healthy males performed incremental cycling exercise to exhaustion with and without intravenous propranolol (18.7 ± 1.9 mg). Lactate concentration was determined in arterial and internal jugular venous blood at the end of each workload. To take changes in arterial lactate into account we calculated the fractional extraction (FELac) defined as AVLac divided by the arterial lactate concentration. Arterial lactate concentration was reduced by propranolol at any workload (p<0.05), reaching 14 ± 3 and 11 ± 3 mmol l-1 during maximal exercise without and with propranolol, respectively. While AVLac and FELac increased during exercise (both P < 0.05), they were both unaffected by propranolol at any workload (= 0.68 and = 0.26) or for any given arterial lactate concentration (P = 0.78 and P = 0.22). These findings support that, while propranolol may reduce cerebral lactate uptake, this effect reflects the propranolol-induced reduction in arterial lactate concentration and not inhibition of a β-adrenergic mechanism within the brain. We hence conclude that cerebral lactate uptake during exercise is directly driven by the increasing arterial concentration with work rate.

Original languageEnglish
JournalJournal of Applied Physiology
Issue number6
Pages (from-to)1824-1830
Number of pages7
Publication statusPublished - 2021

ID: 283840194