Directional sensitivity of the cerebral pressure-flow relationship during forced oscillations induced by oscillatory lower body negative pressure.

A directional sensitivity of the cerebral pressure-flow relationship has been described using repeated squat-stands. Oscillatory lower body negative pressure (OLBNP) is a reproducible method to characterize dynamic cerebral autoregulation (dCA). It could represent a safer method to examine the directional sensitivity of the cerebral pressure-flow relationship within clinical populations and/or during pharmaceutical administration. Therefore, examining the cerebral pressure-flow directional sensitivity during an OLBNP-induced cyclic physiological stress is crucial. We calculated changes in middle cerebral artery mean blood velocity (MCAv) per alterations to mean arterial pressure (MAP) to compute ratios adjusted for time intervals (ΔMCAvT/ΔMAPT) with respect to the minimum-to-maximum MCAv and MAP, for each OLBNP transition (0 to -90 Torr), during 0.05 Hz and 0.10 Hz OLBNP. We then compared averaged ΔMCAvT/ΔMAPT during OLBNP-induced MAP increases (INC) (ΔMCAvT/ΔMAPTINC) and decreases (DEC) (ΔMCAvT/ΔMAPTDEC). Nineteen healthy participants [9 females; 30 ± 6 years] were included. There were no differences in ΔMCAvT/ΔMAPT between INC and DEC at 0.05 Hz. ΔMCAvT/ΔMAPTINC (1.06 ± 0.35 vs. 1.33 ± 0.60 cm⋅s-1/mmHg; p = 0.0076) was lower than ΔMCAvT/ΔMAPTDEC at 0.10 Hz. These results support OLBNP as a model to evaluate the directional sensitivity of the cerebral pressure-flow relationship.

Long-term aerobic exercise training in type two diabetic patients alters the expression of miRNA-223 and its corresponding target, the P2RY12 receptor, attenuating platelet function.

BACKGROUND: Type two diabetes mellitus (T2DM) patients are prone to develop atherothrombotic events due to platelet hyper-reactivity stemming from platelet miRNA-223 down-regulation and over-expression of its corresponding target, P2RY12. OBJECTIVE: The study sought to determine the effects of long-term aerobic training on the expression levels of miRNA-223 and P2RY12 mRNA, and platelet function in T2DM patients. METHODS: Twenty-four patients with T2DM (age, 60.0±2.8 yrs.) were selected and randomly divided into two groups: aerobic exercise training (AET, n = 12) and control (CON, n = 12). The AET protocol was performed with moderate intensity for 12 weeks, while patients in the CON group followed their usual routine. Weight, body mass index (BMI), peak oxygen consumption (VO2peak), lipid profile, fasting blood glucose (FBG), glycated hemoglobin (HbA1c), insulin resistance index (HOMA-IR), platelet miRNA-223 and P2RY12 expression were measured before and after the period. RESULTS: There was a significant improvement in body weight, BMI, VO2peak, FBG, HbA1c, and HOMA-IR, after 12 weeks of AET (P < 0.01). Platelet aggregation decreased significantly after 12 weeks in the AET group compared with the CON (P < 0.001) group. Platelets' miRNA-223 and P2RY12 were significantly up- and down-regulated after AET in comparison with the CON group (P < 0.05), respectively. Moreover, the relative expression of miRNA-223 and P2RY12 significantly correlated with FBG changes following the intervention. CONCLUSIONS: It can be concluded that long-term moderate-intensity aerobic training might be effective for reducing the occurrence of atherothrombotic events leading to premature death in T2DM patients through the modulation of miRNA-223, P2RY12 receptor expression, and platelet function.

Effects of endurance training on hsa-miR-223, P2RY12 receptor expression and platelet function in type 2 diabetic patients.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is associated with thrombotic events due to platelets' defects. OBJECTIVE: The aim of this study was to investigate the effects of endurance training on expressions of platelet hsa-miR-223 and P2RY12 receptor, as well as platelet function in T2DM patients. METHODS: Twenty female T2DM patients (age, 62.25±3.81 yr; weight, 73.53±9.04 kg; height, 154.7±4.3 cm) were randomly divided into two groups (Control (CONT) and endurance training (ET)). Subjects in ET group performed eight weeks of running on treadmill at 60-75% of VO2peak (moderate intensity), 3 sessions per week, while, the subjects in control group were not involved in any kind of exercise training. Two blood samples were taken before and 48 h after the training and were analyzed for platelet aggregation, and hsa-miR-223 and P2RY12 expressions. RESULTS: Although platelet aggregation decreased significantly in ET group (P <  0.05), these changes were not significantly different between two groups. Expression of platelet hsa-miR-223 increased and P2RY12 mRNA reduced following ET non-significantly. However, decreases in fasting blood glucose, glycated hemoglobin and body weight, and increases in VO2peak following ET were significantly different when compared to control group (P <  0.05). CONCLUSIONS: Short-term endurance training dose not induce up-regulation of hsa-miR-223 and down-regulation of P2RY12, while it has a positive impact on platelet function, glycemic indices, physical fitness and body composition in female T2DM patients.

Platelet indices and function response to two types of high intensity interval exercise and comparison with moderate intensity continuous exercise among men after coronary artery bypass graft: A randomized trial.

BACKGROUND: It has been indicated that the acute exercise increases the thrombotic events that stem from platelet hyper-reactivity. The present randomized controlled trial study was carried out with the aim to compare high-intensity interval exercise (HIIE) with moderate intensity continuous exercise (MICE) in terms of platelet indices and function in patients who had undergone post coronary artery bypass graft (CABG). METHODS: 30 men with a history of CABG were recruited and divided into 3 groups (MICE, HIIE-1, and HIIE-2). The MICE protocol consisted of running for 40 minutes with 65% of maximal heart rate (HRmax). Subjects in HIIE-1 group performed an interval exercise with work to rest ratio of 1:1 in which 10 rounds of running (95% HRmax) were followed by active recovery (35% HRmax). HIIE-2 subjects performed an interval exercise with work to rest ratio of 2:1 in which 7 rounds of running (85% HRmax) were followed by active recovery (45% HRmax). Before and immediately after the exercise protocols, blood samples were taken from subjects and analyzed to measure the variables. RESULTS: Although platelet count (PLT) and hematocrit (HCT) were increased significantly after HIIE-1 and HIIE-2 in comparison to MICE (P < 0.050), the other platelet indices [mean platelet volume (MPV), platelet distribution width (PDW), plateletcrit (PCT)] were not significantly changed among groups (P > 0.050). The platelet aggregation and fibrinogen were further increased after HIIE-1 and HIIE-2 as compared with MICE; however, such increment were significant between HIIE-2 and MICE (P < 0.050). CONCLUSION: It seems that HIIE, regardless of the type, has higher thrombotic potentials compared with MICE. Accordingly, MICE is safer than HIIE for rehabilitation in patients undergoing CABG.