These findings provide compelling preclinical evidence for the usage of GH as a potential therapeutic tool in the recovery phase of patients after stroke.
Background and Purpose
Hydroxychloroquine, chloroquine and azithromycin are three drugs that were proposed to treat coronavirus disease 2019 (COVID‐19). While concern already existed around their proarrhythmic potential, there are little data regarding how altered physiological states encountered in patients such as febrile state, electrolyte imbalances or acidosis might change their risk profiles.
Experimental Approach
Potency of human ether‐à‐go‐go related gene (hERG) block was measured using high‐throughput electrophysiology in the presence of variable environmental factors. These potencies informed simulations to predict population risk profiles. Effects on cardiac repolarisation were verified in human induced pluripotent stem cell‐derived cardiomyocytes from multiple individuals.
Key Results
Chloroquine and hydroxychloroquine blocked hERG with IC50 of 1.47 ± 0.07 and 3.78 ± 0.17 μM, respectively, indicating proarrhythmic risk at concentrations effective against severe acute respiratory syndrome‐coronovirus‐2 (SARS‐CoV‐2) in vitro. Hypokalaemia and hypermagnesaemia increased potency of chloroquine and hydroxychloroquine, indicating increased proarrhythmic risk. Acidosis significantly reduced potency of all drugs, whereas increased temperature decreased potency of chloroquine and hydroxychloroquine against hERG but increased potency for azithromycin. In silico simulations demonstrated that proarrhythmic risk was increased by female sex, hypokalaemia and heart failure and identified specific genetic backgrounds associated with emergence of arrhythmia.
Conclusion and Implications
Our study demonstrates how proarrhythmic risk can be exacerbated by metabolic changes and pre‐existing disease. More broadly, the study acts as a blueprint for how high‐throughput in vitro screening, combined with in silico simulations, can help guide both preclinical screening and clinical management of patients in relation to drugs with potential to prolong repolarisation.
Post-stroke cognitive impairment has proven to be notoriously difficult to treat. In the current study, we sought to both better understand cellular changes that underpin cognitive deficits and to consider the potential restorative benefits of low oxygen post conditioning (LOPC).We were motivated to use LOPC as an intervention as it is one of the few experimental interventions previously shown to improve cognitive function post-stroke. Experimental stroke was induced by photothrombotic occlusion in adult male C57BL/6 mice. Mice were randomly assigned to either a normal atmospheric air exposure or low oxygen (11% O 2 ) exposure groups three days post-occlusion. On day 17 post-stroke, mice were euthanized for histology or biochemical analyses. Stroked mice exposed to LOPC was associated with marked reductions in amyloid-beta both in its absolute level and in the extent of its oligomerization. Exposure to LOPC post-stroke also improved cellular deficits induced by stroke including an increase in vessel density, a reduction in vascular leakage, and restoration of AQP4 polarisation. Critically, stroked mice exposed to LOPC exhibited robust improvements in cognitive function post-stroke, assessed using a touchscreen based pairedassociate learning task. These findings provide compelling pre-clinical evidence of the potential clinical utility of LOPC for enhancing recovery post-stroke.
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