Myocardial protection of immature rabbits: polarizing versus depolarizing.
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.
Wang
Jiangang
J
Department of Cardiac Surgery, Anzhen Hospital of the Capital University of Medicine, Beijing (100029), P.R.China. xinlingtianshi7545@sina.com
Zhou
Xinmin
X
Zhao
Yuan
Y
Tang
Hao
H
Hu
Yerong
Y
D000375:Aging; D000818:Animals; D001639:Bicarbonates / Q000008:administration & dosage; D001834:Body Water; D002122:Calcium Chloride / Q000008:administration & dosage; D002316:Cardiotonic Agents / Q000008:administration & dosage*; D003326:Coronary Circulation / Q000187:drug effects; D003402:Creatine Kinase / Q000378:metabolism; D005260:Female; D006324:Heart Arrest, Induced / Q000379:methods*; D006439:Hemodynamics; D006947:Hyperkalemia; D008274:Magnesium / Q000008:administration & dosage; D008297:Male; D008854:Microscopy, Electron; D017202:Myocardial Ischemia; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000648:ultrastructure; D020110:Pinacidil / Q000008:administration & dosage; D011189:Potassium Chloride / Q000008:administration & dosage; D011817:Rabbits; D012965:Sodium Chloride / Q000008:administration & dosage
D001639:Bicarbonates; D002316:Cardiotonic Agents; C041711:St. Thomas' Hospital cardioplegic solution; D012965:Sodium Chloride; D011189:Potassium Chloride; D020110:Pinacidil; D003402:Creatine Kinase; D008274:Magnesium; D002122:Calcium Chloride