HYPERPROLIFERATION OF AORTIC SMOOTH-MUSCLE CELLS AND FIBROBLASTS FROMYOUNG SHR RATS IS NOT SHARED BY ENDOTHELIAL-CELLS

1. To study the hypertensive genotypic influence on growth kinetics of the three aortic wall cell types. 2. Using young spontaneously hypert ensive (SHR) and Wistar-Kyoto (WKY) rats weighing 160-180 g, we compar ed the proliferative properties of endothelial cells (EC), smooth musc le cells (SMC) and fibroblasts that were isolated from the thoracic ao rta of each strain and cultured. Growth-arrested cells were exposed to P<-thymidine after stimulation with 150 mu g/mL endothelial cell. gro wth supplement. Proliferation assays were performed by cell seeding on decellularized aortic explants and cell counting 2, 4, 5, 6 and 7 day s after seeding. The influence of SMC from SHR on the growth kinetics of EC was evaluated by co-cultures in transwell systems. 3. After stim ulation, SMC from SHR exhibited a greater P<-thymidine incorporation r ate than those from WKY rats (ratios over controls: 3.90+/-0.48 [7] vs 1.85+/-0.25 [7] respectively P<0.05). This was also true for adventit ial SHR fibroblasts: (13.1+/-0.6 [6] vs 9.9+/-1.0 [6] WKY P<0.05), On the contrary, there was no difference in the P<-thymidine incorporatio n rates between EC of each strain, regardless of the passage and the t ime considered. Cell proliferation on matrix explants confirmed the hy perproliferation of SMC and fibroblasts from SHR, while EC of each str ain proliferated equally. Smooth muscle cells from SHR did not influen ce the growth kinetics of EC in co-culture and vice versa. 4. The chan ges in growth patterns of aortic cells isolated from young prehyperten sive SHR seem to be restricted to SMC and fibroblasts.