Background: Remote ischemic preconditioning (RIP) represents a novel form of innate cardioprotection conferred by short episodes of ischemia applied in a distant organ/tissue. Efficiency of RIP in increasing myocardial resistance against ischemia-reperfusion (I/R) injury has been shown in 3-months old male rats with RIP applied either directly prior to I/R or 24-h before ischemia. However, there is no evidence on the effects of RIP in hearts from spontaneously hypertensive (SHR) rats. This study aimed to investigate the effect of RIP on cardiac tolerance to I/R in male SHR rats of different ages.
Methodology: Rats of age three, five and eight months were anesthetized and RIP was performed on the right hind limb. Its protocol consisted of three cycles of 5-min non-invasive limb occlusion followed by 5-min reperfusion. Subsequently, hearts were excised, Langendorff-perfused and exposed to 30-min global I and 2-h R for the evaluation of reperfusion-induced ventricular arrhythmias, infarct size and recovery of contractile function.
Results: Only hearts five months old SHR rats exposed to RIP protocol exhibited significantly improved recovery of contractile function (LVDP). On the other hand, enhanced resistance to myocardial infarction compared to non-preconditioned animals was observed in all experimental groups. Moreover, in three and five months old animals RIP exhibited antiarrhythmic effect, while its impact on arrhytmogenesis in eight months old SHR rats was negative.
Conclusions: RIP may represent an effective protecting stimulus in the hearts of SHR animals. Cardioprotective effects of RIP in SHR rats show partial age-dependency, since in older adult animals, RIP decreased size of lethal injury but failed to improve recovery of contractile function and even worsened arrhythmogenesis compare to younger adults. RIP may influence various aspects of I/R injury in different way.
Grants: VEGA2/0201/15, APVV-0102-11, APVV-SK-CZ-2013-0075.