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Can exercise training enhance the repeated remote ischaemic preconditioning stimulus on peripheral and cerebrovascular function in high-risk individuals?
Maxwell, JD, France, M, Finnigan, LEM, Carter, HH, Thijssen, DHJ, Jones, H
European journal of applied physiology. 2021;(4):1167-1178
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Abstract
BACKGROUND Repeated exposure to remote ischaemic preconditioning (rIPC; short bouts of non-lethal ischaemia) enhances peripheral vascular function within 1 week; whereas, longer periods of rIPC (~ 1 year) may improve cerebral perfusion. Increasing the 'dose' of rIPC may lead to superior effects. Given the similarities between exercise and rIPC, we examined whether adding exercise to the rIPC stimulus leads to greater adaptation in systemic vascular function. METHODS Nineteen individuals with increased risk for cardiovascular disease (CVD) were randomly allocated to either 8 weeks of rIPC (n = 9) or 8 weeks of rIPC + exercise (rIPC + Ex) (n = 10). rIPC was applied three times per week in both conditions, and exercise consisted of 50 min (70% heart rate max) of cycling 3 times per week. Peripheral endothelial function was assessed using flow-mediated dilation (FMD) before and after ischaemia-reperfusion (IR). Cerebrovascular function was assessed by dynamic cerebral autoregulation (dCA) and cerebrovascular reactivity (CVR), and cardio-respiratory fitness (VO2peak) using a maximal aerobic capacity test. RESULTS FMD% increased by 1.6% (95% CI, 0.4, 2.8) following rIPC + Ex and by 0.3% (- 1.1, 1.5) in the only rIPC but this did not reach statistical significance (P = 0.65). Neither intervention evoked a change in dCA or in CVR (P > 0.05). VO2peak increased by 2.8 ml/kg/min (1.7, 3.9) following the rIPC + Ex and by 0.1 ml/kg/min (- 1.0, 1.4) following the rIPC only intervention (P = 0.69). CONCLUSION Combining exercise with rIPC across an 8-week intervention does not lead to superior effects in cerebrovascular and peripheral vascular function compared to a repeated rIPC intervention in individuals at risk of CVD.
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Bradykinin preconditioning in coronary artery bypass grafting.
Wei, M, Wang, X, Kuukasjärvi, P, Laurikka, J, Rinne, T, Honkonen, EL, Tarkka, M
The Annals of thoracic surgery. 2004;(2):492-7
Abstract
BACKGROUND Experimental studies have shown that activation of bradykinin B2 receptor is one of the most important triggers of ischemic preconditioning. However, the effect of exogenous administration of bradykinin in cardiac surgery is not yet known. The present prospective randomized study was designed to investigate the effect of bradykinin pretreatment in patients undergoing elective coronary artery bypass surgery. METHODS Forty-one patients with multiple-vessel coronary artery disease and stable angina, admitted for the first time for elective coronary artery bypass surgery, were randomized into control or bradykinin (BK) groups. Patients in the BK group received bradykinin infusion for 7 minutes (total dose 25 microg) before the initiation of cardiopulmonary bypass. Perioperative cardiac specific troponin I (cTnI) and creatine kinase cardiac isoenzyme (CKMB) release and hemodynamics were recorded. RESULTS Bradykinin infusion caused acute decrease of blood pressure in most of the cases and the mean minimum mean blood pressure during bradykinin infusion was 72.7% of the original mean blood pressure (MBP) level (74.7 +/- 7.9 vs 54.4 +/- 12.1 mm Hg, p < 0.01). There were no differences in baseline levels of cTnI and CKMB between the groups. The postoperative cTnI levels were lower than 10 ng/mL in most patients in both groups (18 in the BK group and 15 in the control group). There was no difference in cTnI between the groups. However, patients who received bradykinin released significantly less CKMB than did the controls postoperatively (6 hours, BK, 22.1 +/- 9.5 vs control, 23.6 +/- 12.7 U/L; 12 hours, BK, 19.4 +/- 12.4 vs control, 28.7 +/- 23.8 U/L; 24 hours, BK, 21.5 +/- 14.7 vs control, 35.5 +/- 28.9 U/L; 48 hours, BK, 14.4 +/- 7.5 vs control, 23.5 +/- 13.6 U/L; analysis of variance [ANOVA] for repeated measurement, p = 0.036). Maximum CKMB was also lower in the BK group (22.4 +/- 14.4 vs 37.7 +/- 27.5 U/L, p = 0.044). There was no significant difference between the groups in any of the hemodynamic variables. CONCLUSIONS Exogenous bradykinin infusion showed weak cardioprotective effect in the low-risk patients undergoing coronary artery bypass surgery but the dose used in the study caused acute decrease of systemic blood pressure.