The role of protein kinase C and PI3-kinase in the mechanism of the cardioprotective effect of remote ischemic postconditioning

Background. Acute myocardial infarction (AMI) with ST segment elevation is associated with high incidence of complications. Mortality from AMI is about 5%, which has not decreased in recent years. Revascularization provides recovery of coronary blood flow, but also contributes to the occurrence of reperfusion injury to the heart. Remote ischemic postconditioning (RIPostC) is a promising, non-invasive method that can effectively and safely reduce the infarct size.The aim of the study was to investigate the role of protein kinase C and PI3-kinase in the development of the infarct-limiting effect of remote ischemic postconditioning.Materials and methods. The study was performed on Wistar rats. Coronary artery occlusion (45 min) and reperfusion (2 h) were performed. The infarct size (IS) and the size of area at risk (AAR) were assessed. RIPostC was modeled by applying tourniquets to the hind limbs in the hip joint immediately after the restoration of coronary blood flow. All inhibitors were administered intravenously 10 min before reperfusion.Results. In the control group, the IS / AAR ratio was 44%. RIPostC reduced the IS / AAR ratio by about 50%. Preliminary administration of the protein kinase C inhibitor chelerythrine and the PI3-kinase inhibitor wortmannin eliminated the cardioprotective effect of RIPostC.Conclusion. The mechanism of the infarct-limiting effect of RIPostC is implemented through activation of protein kinase C and PI3-kinase.

Remote Ischemic Postconditioning vs. Physical Exercise After Stroke: an Alternative Rehabilitation Strategy?

There remain debates on neuroprotection and rehabilitation techniques for acute ischemic stroke patients. Therapeutic physical exercise following stroke has shown promise but is challenging to apply clinically. Ischemic conditioning, which has several clinical advantages, is a potential neuroprotective method for stroke rehabilitation that is less understood. In the present study, the rehabilitative properties and mechanisms of physical exercise and remote ischemic postconditioning (RIPostC) after stroke were compared and determined. A total of 248 adult male Sprague-Dawley rats were divided into five groups: (1) sham, (2) stroke, (3) stroke with intense treadmill exercise, (4) stroke with mild treadmill exercise, and (5) stroke with RIPostC. Focal ischemia was evaluated by infarct volume and neurological deficit. Long-term functional outcomes were represented through neurobehavioral function tests: adhesive removal, beam balance, forelimb placing, grid walk, rota-rod, and Morris water maze. To further understand the mechanisms underlying neurorehabilitation and verify the presence thereof, we measured mRNA and protein levels of neuroplasticity factors, synaptic proteins, angiogenesis factors, and regulation molecules, including HIF-1α, BDNF, TrkB, and CREB. The key role of HIF-1α was elucidated by using the inhibitor, YC-1. Both exercise intensities and RIPostC significantly decreased infarct volumes and neurological deficits and outperformed the stroke group in the neurobehavioral function tests. All treatment groups showed significant increases in mRNA and protein expression levels of the target molecules for neurogenesis, synaptogenesis, and angiogenesis, with intermittent further increases in the RIPostC group. HIF-1α inhibition nullified most beneficial effects and indicative molecule expressions, including HIF-1α, BDNF, TrkB, and CREB, in both procedures. RIPostC is equally, or superiorly, effective in inducing neuroprotection and rehabilitation compared to exercise in ischemic rats. HIF-1α likely plays an important role in the efficacy of neuroplasticity conditioning, possibly through HIF-1α/BDNF/TrkB/CREB regulation.

Safety and efficacy of remote ischemic postconditioning after thrombolysis in patients with stroke

ObjectiveTo determine the effect of remote ischemic postconditioning (RIPC) on patients with acute ischemic stroke (AIS) undergoing IV thrombolysis (IVT).MethodsA single-center randomized controlled trial was performed with patients with AIS receiving IVT. Patients in the RIPC group were administered RIPC treatment (after IVT) during hospitalization. The primary endpoint was a score of 0 or 1 on the modified Rankin scale (mRS) at day 90. The safety, tolerability, and neuroprotection biomarkers associated with RIPC were also evaluated.ResultsWe collected data from both the RIPC group (n = 34) and the control group (n = 34). The average duration of hospitalization was 11.2 days. There was no significant difference between 2 groups at admission for the NIH Stroke Scale score (p = 0.364) or occur-to-treatment time (p = 0.889). Favorable recovery (mRS score 0–1) at 3 months was obtained in 71.9% of patients in the RIPC group vs 50.0% in the control group (adjusted odds ratio 9.85, 95% confidence interval 1.54–63.16; p = 0.016). We further found significantly lower plasma S100-β (p = 0.007) and higher vascular endothelial growth factor (p = 0.003) levels in the RIPC group than in the control group.ConclusionsRepeated RIPC combined with IVT can significantly facilitate recovery of nerve function and improve clinical prognosis of patients with AIS.ClinicalTrials.gov identifierNCT03218293.Classification of evidenceThis study provides Class IV evidence that RIPC after tissue plasminogen activator treatment of AIS significantly increases the proportion of patients with an MRS score of 0 or 1 at 90 days.