CELL TO STROMA CONTACTS IN THE TUNICA MEDIA OF THE HYPERTENSIVE RAT THORACIC AORTIC

The variation in mechanical stress to which the aortic wall is subject ed requires that forces be transmitted between its components by means of relatively strong but compliant attachments, We have used transmis sion electron microscopy in order to study the cell to stroma contacts (smooth muscle cell-elastic fiber contact) in the tunica media of nor motensive and hypertensive aortas of Sprague-Dawley rats, Hypertension was produced with a silver clip positioned around the left renal arte ry and the vessels were fixed by intravital perfusion at normal and el evated pressure, In ultrathin sections, the density of cell to stroma contacts per 100 mu m cell perimeter and per 100 cell profiles were de termined using an image analysis computer, In the hypertensive group t he density of cell to stroma contacts fell considerably when compared with the control group, This research provides insights into the condi tions under which high blood pressure may produce medial injuries and, perhaps, be a factor in the precipitation of dissections.