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

Study 4- Second window of protection
In Chapter 2,1 showed that the right atrial preparation used in the present experiments is viable
for at least 24 hours-, however, after this time the preparation is more susceptible to
ischemia/reperfusion
injury than when incubated for shorter periods. For this reason, in this study
two different periods of ischaernia, 30 (moderate ischaemia) and 90 min (severe ischaemia), were
used to investigate the late or second window of protection of i%chaemic preconditioning.
Figures 3 9A and 3.913 show the results with 30 min ischaernia. Ischaernia alone caused a
significant increase in CK leakage and decrease in MTT reduction when compared with the
aerobic control group. Both the first and second window of protection gave a similar decrease in
CK leakage and amelioration of MTT reduction
As shown in Figures 3.10A and 3.1013, extension of the period of ischaernia to 90 min resulted in
greater CK leakage and lower VITT reduction than with 30 min ischaernia. As expected, the first
window of preconditioning significantly improved CK leakage and MTT reduction, however, this
beneficial effect was not seen with the second window of preconditioning and values were similar
to those observed in the ischaernia alone group.
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