DNA synthesis and apoptosis in smooth muscle cells from a model of genetichypertension

The present study was designed to assess vascular smooth muscle cell (VSMC) proliferation and apoptosis in primary cultured VSMCs prepared from the ao rtic tunica media of adult (4 to 5 months old) age- and gender-matched grou ps of stroke-prone spontaneously hypertensive rats (SHRSP) and the normoten sive reference strain, Wistar-Kyoto (WKY) rats. In the present study, VSMC proliferation was assessed with measurement of DNA synthesis in response to stimulation of G(0)/G(1) arrested VSMCs with 10% serum, whereas apoptosis was measured in response to serum deprivation. Apoptosis in aortic VSMCs wa s assessed in vitro with the technique of Annexin V binding in combination with propidium iodide exclusion with bivariate flow cytometric analysis. Th e percentage of necrotic VSMCs in the cell populations was assessed simulta neously. The light-scattering properties of the cells were assessed to prov ide further information on cell shrinkage and chromatin condensation. Resul ts of the present study have shown enhanced DNA synthesis in VSMCs from SHR SP (n=10; 5.2+/-0.9 cpmx10(3)/mg protein) compared with WKY (n=12; 2.4+/-0. 7 cpmx10(3) /mg protein; P<0.05, 95% CI, -5271 to -296). In addition, the r esults of the present study have demonstrated the role of serum in the surv ival of VSMCs in vitro, because SHRSP VSMCs underwent significantly more ap optosis in response to insult by serum deprivation (n=13; 10.21+/-1.8%) tha n WKY VSMCs (n=7; 3.44+/-1.4%; P<0.01, 95% CI, -11.5 to -2.0). Thus, it app ears that both proliferation and apoptosis are enhanced in synthetic phenot ype aortic medial VSMCs from the SHRSP in vitro.