ischaemic preconditioning of the human heart. - Leicester Research ...

clearly insufficient to induce myocardial injury. Furthermore, during this short
period of sample processing the muscles are not preconditioned when subjected to a
long period of ischaernia.
Studies on Ischaernia:
To the best of my knowledge, the present studies are the first in charactensing the
response of the human myocardium to various degrees of ischaernic insult. I have
demonstrated
that a period of simulated ischaernia of only 30 min already induces
significant tissue injury, as measured by MTT reduction and LDH leakage, and that
lengthening the ischaernic time to 2 hr results in a loss of viable tissue of more than
75% and massive LDH leakage. it is worth noting that the reduction in oxygen
consumption observed after 30 min of ischaemla was not further decreased by 60 or
120 min of ischaernia. This suggests that in fact the remaining viable tissue
augments oxygen consumption when compared to aerobically perfused tissue or to
tissue subjected to shorter periods of ischaernia. This phenomenon of oxygen
sparing effect after ischaemia has been described in various animal preparations
[43,73,162,184] suggesting that it may not be a reliable index of tissue damage.
It is evident from these studies and, not unexpected, that although the atfial
myocardium aerobically incubated for 24 hr is still viable it becomes more
susceptible to ischaemic injury. This observation is of particular relevance when
investigating the delayed effects of ischaemic syndromes such as the second window
of ischaernic preconditioning.
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