Absence of apparent cardioprotection following ischemic preconditioning in immature rabbit hearts

Remote ischemic preconditioning in cyanosed neonates undergoing cardiopulmonary bypass: A randomized controlled trial

“…14 Preconditioning has been demonstrated to be protective in mature myocardium in both animal and human studies; however, doubts have been raised regarding the efficacy of preconditioning on the newborn and immature myocardium, with conflicting data from animal studies. Bin and colleagues 15 showed no protection against IR injury with preconditioning in a juvenile rabbit model (aged 14-21 days). In a rat model, Awad and colleagues 16 demonstrated that protection against IR injury was provided by preconditioning after 7 days of age but not before.…”

Remote ischemic preconditioning impairs ventricular function and increases infarct size after prolonged ischemia in the isolated neonatal rabbit heart

“…For example, some studies have shown that the ability to achieve cardioprotection from local ischemic preconditioning is not present in fetal life and only becomes apparent after 1 to 4 weeks (depending on the species) after birth. [5][6][7] However, others have shown effective pharmacologic and ischemic preconditioning in immature rabbit hearts 8 and isolated neonatal cardiomyocytes. 9,10 Given the contrasting data, it is unsurprising that the mechanisms underlying ''preconditioning resistance'' remain unknown, although the immature myocardium consistently appears intrinsically more resistant to hypoxia and possibly ischemia, 6,11 raising the possibility that it is already ''preconditioned'' in some way.…”

Ischaemic preconditioning: Developing knowledge of a developing process

“…he phenomenon of ischaemic preconditioning (IP), in which brief periods of ischaemia result in increased tissue resistance to ischaemic injury, was first described in the heart in 1986 1 . In this issue of Heart, Lung and Circulation , Bin and coworkers present data suggesting that this phenomenon, which we increasingly recognise plays a powerful protective role in the adult heart, may be absent in the neonate 2 . In hearts from 14−21‐day‐old rabbits, perfused in the Langendorff mode, Bin et al .…”