Structural changes in the freeze-fractured sarcolemma of ischemic myocardium.
Ultrastructural alterations in the sarcolemma of ischemic myocardium were studied with the freeze-fracture technique. In normal myocardial sarcolemma, the P fracture face contained many intramembranous particles which were randomly distributed, while the E fracture face had few intramembranous particles; no structural abnormalities were seen within the lipid bilayer on either face. Myocardium ischemic for 45 minutes displayed no, or only slight, aggregation of intramembranous particles, but upon reperfusion for 5 to 20 minutes, the particles became significantly aggregated in the P face. Scattered nicks within the lipid bilayer were observed on both fracture faces. Intramembranous particles were similarly aggregated in myocardium ischemic for 2 hours; however, the number of nicks were greatly increased on the P and E fracture faces. These structural alterations, which were undetected in thin sections, are likely to be associated with altered function in the sarcolemma of ischemic myocardium.
D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D003327:Coronary Disease / Q000473:pathology*; D004285:Dogs; D005614:Freeze Fracturing; D002479:Inclusion Bodies / Q000648:ultrastructure; D050356:Lipid Metabolism; D009206:Myocardium / Q000473:pathology* / Q000648:ultrastructure; D012508:Sarcolemma / Q000648:ultrastructure*