The Effects of Remote Ischemic Preconditioning on Cognitive Function and Exercise Hyperemia in Isocapnic Hypoxia

Abstract

Impairments in neurological and skeletal muscle function can occur in conditions of decreased oxygen delivery and vascular dysfunction can exacerbate any impairments. Remote ischemic preconditioning (RIPC) has been used to improve vascular functioning during exercise and cognitive tasks, but this intervention has yet to be tested in hypoxic conditions. Here, we test the hypothesis that RIPC can attenuate the hypoxia‐induced decline in cognitive function and also impact forearm blood flow during hypoxic exercise. Healthy, young men and women participated in two counterbalanced experimental sessions, consisting of two trials of rhythmic dynamic handgrip exercise (4 min, 10% maximal voluntary contraction) followed by computerized cognitive testing, once in normoxia (21% inspired O2), and once in isocapnic hypoxia (target O2 saturation ~85% via pulse oximetry). The cognitive tests (CNS Vital Signs) measured composite memory, verbal memory, visual memory, and processing speed. During rest and handgrip exercise, forearm blood flow (FBF) responses were determined via Doppler ultrasound and muscle oxygenation was assessed using near infrared spectroscopy (Moxy). Systemic hemodynamics [heart rate (ECG) and non‐invasive beat‐to‐beat blood pressure (Finometer)] were collected throughout. One experimental session consisted of RIPC (4 × 5 min thigh cuff inflation; 200 mmHg) between the normoxic and hypoxic trials whereas the other was a sham (~10 mmHg cuff pressure) intervention. Percent change (%Δ) from normoxia to hypoxia was determined for cognitive test scores. Preliminary results (n=6, mean±sem) demonstrate modest hypoxia‐induced declines in composite, verbal, and visual memory (−8.6±4.4%, −11.2±6.6%, −5.2±3.8%) but not processing speed in sham conditions. The RIPC intervention had no consistent impact on these hypoxia‐induced changes. Exercise hyperemia was increased in hypoxia vs normoxia (177±12 vs 163±6 ml/min in hypoxia vs normoxia, respectively) and RIPC modestly increased exercise hyperemia in hypoxia (191±10 ml/min) but had little effect during normoxia (167±12 ml/min). We conclude that RIPC has a minimal effect on the impact of hypoxia on cognitive function and can augment hypoxic exercise hyperemia in young, healthy humans.Support or Funding InformationUniversity of Dayton University Honors Program, Berry Summer Thesis Institute (JNS)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.