ULTRASTRUCTURAL-LOCALIZATION OF NITRIC-OXIDE SYNTHASE, ENDOTHELIN ANDBINDING-SITES OF LECTIN (FROM BANDEIREA-SIMPLICIFOLIA) IN THE RAT CAROTID-ARTERY AFTER BALLOON CATHETER INJURY

An immunocytochemical and cytochemical study has been made on the ultr astructural localisation of type III (endothelial) nitric oxide syntha se, endothelin-1 and the binding sites of lectin from Bandeirea simpli cifolia to the endothelium surface-associated glycoproteins in the rat left common carotid artery at 1 and 28 d after Fogarty embolectomy ba lloon catheter-induced injury. Controls were carotid arteries from sha m operated rats. In the controls, the immunoreactivity to nitric oxide synthase-III and endothelin-l was localised in different proportions in vascular endothelial cells (36.9%+/-4.3 and 7.6%+/-2.7, respectivel y); immunoreactivity was confined to the cytoplasm and the membranes o f intracellular organelles and structures. In contrast, staining with lectin was localised on the luminal surface of all endothelial cells. 1 d after injury, platelets were adherent to the endothelium-denuded i ntima. Some of the platelets displayed immunoreactivity to nitric oxid e synthase-III and endothelin-1 and were stained with lectin. 28 d aft er injury, a neointimal thickening of substantial size was present. Su bpopulations of the regrown endothelial cells covering the luminal sur face of the neointima showed positive immunoreactivity to nitric oxide synthase-III and endothelin-1 but there was a significant decrease in the proportion of nitric oxide synthase-III-containing endothelial ce lls (17.2%+/-1.9; P < 0.001) and a significant increase in the proport ion of endothelin-1-containing endothelial cells (36.9%+/-4.7; P < 0.0 01) compared with the controls. Staining with lectin was associated wi th the cell membrane of all endothelial cells and in addition with cel ls located 'deeper' in the neointima which showed lectin-positive plas malemma, Golgi complex and multivesicular bodies/lysosomes. In conclus ion, regenerated endothelial cells of the neointima showed reduced pop ulation (2-fold) of nitric oxide synthase-III- and increased populatio n (5-fold) endothelin-1-positive cells. The subendothelial location of some lectin-stained cells after balloon catheter injury indicates the heterogeneity of the neointima and suggests that some of these cells are involved in early angiogenesis. 24 h and 28 d after injury some pl atelets showed positive immunoreactivity for nitric oxide synthase-III and endothelin-1.