Evidence for transcytosis of exogenous superoxide dismutase and catalase from coronary capillaries into dog myocytes.
Infusion of superoxide dismutase (SOD) and catalase (CAT) into the coronary circulation protects myocardial tissue from free radical injury and improves recovery of myocardial function after a short episode of ischaemia. To investigate the ultrastructure of myocardium treated with SOD and CAT, these enzymes were injected into the left atrium of dogs prior to and during 15 min of regional myocardial ischaemia, allowing 30 min of reperfusion, and then fixing the tissue for electron microscopy. The exogenous SOD + CAT was found to promote recovery of both function and structure in these hearts. In addition, electron dense material was unexpectedly found in vesicles of capillary endothelia, between capillaries and myocyte, and in vesicles within myocytes. This occurred only in hearts treated with SOD and/or CAT, suggesting SOD and CAT was concentrated and transported across the capillary endothelium and into myocytes. The rate of transcytosis, as measured by the number of intra-endothelial vesicles, was increased in tissue subjected to ischaemia and reperfusion in the presence of SOD and CAT. These observations suggest transcytosis of SOD and CAT is an important part of the process by which these enzymes provide protection to myocardium during reperfusion after ischaemia.
Chudej
L L
LL
Department of Biology, Southwest Texas State University, San Marcos 78666.
Koke
J R
JR
Bittar
N
N
D000818:Animals; D001692:Biological Transport; D002196:Capillaries / Q000378:metabolism; D002374:Catalase / Q000493:pharmacokinetics* / Q000627:therapeutic use; D004285:Dogs; D004730:Endothelium, Vascular / Q000378:metabolism*; D005260:Female; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D013482:Superoxide Dismutase / Q000493:pharmacokinetics* / Q000627:therapeutic use
D002374:Catalase; D013482:Superoxide Dismutase