Different preservation of myocardial capillary endothelial cells and cardiomyocytes during and after cardioplegic ischemia (25 degrees C) of canine hearts.
Complete resumption of cardiac function after cardioplegic arrest presupposes a well-preserved myocardial ultrastructure during and after ischemia. Therefore, we determined ischemia-induced ultrastructural alterations in the myocardium during and after reversible cardioplegic ischemia using stereological methods. Cardiac arrest was induced with St. Thomas' Hospital- or Custodiol (HTK) solution. Reperfusion with Tyrode's solution followed after reversible cardioplegic ischemia in situ. Samples were taken 1) from beating hearts, 2) from cardioplegically arrested hearts immediately after the end of coronary perfusion, 3) from ischemic hearts incubated in the cardioplegic solution at 25 degrees C, and 4) from reperfused beating hearts after ischemia in situ at 22 degrees C. Cellular swelling was determined as the barrier thickness of capillary endothelium and as the sum of cardiomyocyte volume fractions of free sarcoplasm and mitochondria. In St. Thomas'-arrested hearts, intraischemic volume increase was significantly more pronounced in endothelial cells than in cardiomyocytes. Reperfusion at the intraischemic practical limit of resuscitability (ATP levels of 4 micromol/gww) significantly reduced intraischemic swelling of cardiomyocytes, but not of capillary endothelial cells. Mitochondrial damage was more pronounced in capillary endothelial cells during ischemia and after reperfusion. Thus, after reversible cardioplegic arrest, structural recovery of cardiomyocytes is better than that of capillary endothelial cells. An incomplete structural protection of capillary endothelial cells may predominantly contribute to postischemic dysfunction in the reperfused heart.
Schmiedl
A
A
Department of Anatomy, Division of Electron Microscopy, University of Göttingen, Germany. Schmiedl.Andreas@MH-Hannover.de
Richter
J
J
Schnabel
Ph A
PA
D000818:Animals; D001639:Bicarbonates / Q000627:therapeutic use; D002122:Calcium Chloride / Q000627:therapeutic use; D002314:Cardioplegic Solutions; D004285:Dogs; D004730:Endothelium, Vascular / Q000187:drug effects / Q000648:ultrastructure*; D005260:Female; D005947:Glucose / Q000627:therapeutic use; D006324:Heart Arrest, Induced; D008274:Magnesium / Q000627:therapeutic use; D008297:Male; D008353:Mannitol / Q000627:therapeutic use; D008854:Microscopy, Electron; D008929:Mitochondria, Heart / Q000187:drug effects / Q000648:ultrastructure*; D017202:Myocardial Ischemia / Q000378:metabolism / Q000473:pathology*; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D009206:Myocardium / Q000378:metabolism / Q000648:ultrastructure*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure*; D011189:Potassium Chloride / Q000627:therapeutic use; D011343:Procaine / Q000627:therapeutic use; D012965:Sodium Chloride / Q000627:therapeutic use
D001639:Bicarbonates; C039984:Bretschneider cardioplegic solution; D002314:Cardioplegic Solutions; C041711:St. Thomas' Hospital cardioplegic solution; D008353:Mannitol; D012965:Sodium Chloride; D011343:Procaine; D011189:Potassium Chloride; D008274:Magnesium; D005947:Glucose; D002122:Calcium Chloride