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Myocardial protection of immature rabbits: polarizing versus depolarizing
Jiangang Wang1, Xinmin Zhou, Yuan Zhao
1Department of Cardiac Surgery, Anzhen Hospital of the Capital University of Medicine, Beijing (100029), P.R.China. xinlingtianshi7545@sina.com
Background:
This study was designed to identify the potassium-channel opener pinacidil as a cardioplegic agent vs hyperkalemic cardioplegia in terms of its efficacy in immature cardioprotection.
Methods:
By a Langendorff model, 21 hearts of 21- to 28-day-old New Zealand rabbits underwent 90 min of global hypothermic (15 degrees C) ischemia protected with a different single dose of hypothermic (4 degrees C) cardioplegia (pinacidil [50 micromol/l], St. Thomas' solution combined with pinacidil [50 micromol/l], and St. Thomas' solution). The percent recovery of the cardiac function, creatine kinase release, and cellular ultrastructure were compared.
Results:
Pinacidil (50 micromol/l) provided significantly the best postreperfused percentage recovery of the function than the other groups; pinacidil cardioplegia showed a significant reduction of creatine kinase release in the coronary flow compared with the other groups; St. Thomas' solution combined with pinacidil showed the highest release. Percentage recovery of the coronary flow, water contents, and ultrastructural changes were similar between the groups.
Conclusions:
Pinacidil provided better protection during ischemia-reperfusion in the immature rabbit heart than St. Thomas' solution, whereas pinacidil combined with St. Thomas' solution showed the worst protective effects in immature hearts.