title: Ultrastructural, immunochemical and electrophoretic study of smooth muscle cells in internal mammary arteries of patients undergoing coronary bypass surgery.
abstract: The internal mammary artery (IMA) is used widely in bypass grafting for coronary artery disease because of its resistance to atherosclerotic obstruction. Since there are no data on the ultrastructure of IMA or the phenotype of its smooth muscle cells (SMC), we studied the distal parts of left IMA obtained at the time of surgery from 14 coronary bypass patients, aged 43-67 years. Eight IMA were examined by transmission electron microscopy. The distribution of the cytoskeletal proteins actin, vimentin, and desmin in the intima-media of 6 IMA was studied by immunofluorescence microscopy, polyacrylamide gel electrophoresis, and two-dimensional gel electrophoresis. The intimas were very thin, from 3 to 32 microns. The thinnest regions contained no cells. Most intimal cells had the ultrastructural features of SMC; no foam cells were found. The majority of both intimal and medial SMC had a myofilament-rich phenotype. Cells reacting to antibodies of vimentin, desmin and alpha-actin were found in both intima and media. alpha-Actin formed 67% of all actin isoforms in the intima-medial extracts. Our study confirms ultrastructurally the reported scarcity of atherosclerosis in the human IMA and shows that the majority of SMC in the IMA of even severely atherosclerotic coronary bypass patients are both ultrastructurally and biochemically in a differentiated state, which agrees with their resistance to atherosclerosis.
authors.affiliation: Department of Biomedical Sciences, University of Tampere, Finland.
authors.forename: S T
authors.initials: ST
authors.lastname: Nikkari
authors.forename: T
authors.initials: T
authors.lastname: Sisto
authors.forename: T
authors.initials: T
authors.lastname: Nikkari
mesh_terms: D000199:Actins / Q000378:metabolism; D000328:Adult; D000368:Aged; D001161:Arteriosclerosis / Q000473:pathology; D001026:Coronary Artery Bypass; D003893:Desmin / Q000378:metabolism; D004586:Electrophoresis; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D008297:Male; D008323:Mammary Arteries / Q000166:cytology* / Q000378:metabolism; D008854:Microscopy, Electron; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000378:metabolism; D013895:Thoracic Arteries / Q000166:cytology*; D014746:Vimentin / Q000378:metabolism
chemical_list: D000199:Actins; D003893:Desmin; D014746:Vimentin