[Expression of results in studies of vascular biochemical components during the development of the SHR rat]

Hypertrophy and hyperplasia induced by age and hypertension as well as tissue heterogeneity makes it difficult to analyse biochemical datas obtained with rats thoracic aortas from rats of various age and blood pressure. In SHR, the thoracic aorta weight increases parallely to the body weight from the first week after birth onwards. Meanwhile the protein content of the organ increases parallely to the organ weight. However, though the DNA content increases markedly up to 7 weeks of age, one observes a much lower increase with age afterwards. It seemed to us that the aorta DNA content was more representative of the organ cell number. This led us to use express our biochemical data per mg of the organ DNA content. Moreover, it seems necessary to take in account the cell volume which increases as well with age and hypertension on the one hand, and to be able to distinguish the cellular content of the myocytes from the one of other cells types contained in the adventitia and the intima, on the other hand. For these purposes pure media layers are prepared by completely removing the adventitia and intima and single cell suspensions are obtained after total enzyme digestion of the medias.