Ischaemia causes externalization of endothelin-1 binding sites in rat cardiac membranes.
Specific, high affinity binding sites for iodinated endothelin-1 ([125I]-ET-1) were identified in crude plasma and light membrane fractions harvested from aerobically perfused and ischaemic rat hearts, to determine whether the ischaemia-induced increase in binding site density (Bmax) involves externalization of the sites. In crude plasma membranes Bmax increased after 60 min ischaemia, from 113.5 +/- 2.15 to 180.6 +/- 4.67 fmol/mg protein (p less than 0.01). In the light membranes, the Bmax fell, from 94.7 +/- 8.70 to 63.80 +/- 6.26 fmol/mg protein (p less than 0.05). Hill coefficients and selectivity of both membrane fractions were unchanged. These results are interpreted as meaning that ischaemia causes externalization of cardiac [125I]-ET-1 binding sites.
Liu
J J
JJ
Department of Medicine, University of Melbourne, Austin Hospital, Heidelberg, Victoria, Australia.
Casley
D J
DJ
Nayler
W G
WG
D000332:Aerobiosis; D000693:Anaerobiosis; D000818:Animals; D001667:Binding, Competitive; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism; D003327:Coronary Disease / Q000378:metabolism*; D016232:Endothelins; D004730:Endothelium, Vascular; D005260:Female; D007700:Kinetics; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017466:Receptors, Endothelin; D014461:Ultracentrifugation
D016232:Endothelins; D010455:Peptides; D011956:Receptors, Cell Surface; D017466:Receptors, Endothelin