Gender differences in growth of vascular smooth muscle cells isolated from hypertensive and normotensive rats

Higher male sensitivity to atherosclerotic and hypertensive events was a reason to study sex differences in migration and proliferation of vascular smooth muscle cells (VSMC) isolated from male and female spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) controls. Outgrowth of cells from explants, doubling time, curves of cumulative labeling and the length of cell cycle were measured in aortic VSMC. Systolic and mean arterial pressures were higher in males than in females of the two strains. The migration of cells from male explants was significantly faster than those from female aortas in both strains. The doubling time was always shorter in male VSMC than in those from females and this was more apparent in the late exponential phase of growth. The thymidine incorporation into newly synthesized DNA, which was enhanced in SHR compared to WKY cells, was also higher in male cells compared to female ones. Cell cycle was always shorter in male than in female VSMC due to the shorter G1 phase. In contrast, shorter S phase caused shorter cell cycle in SHR compared to WKY VSMC. Consequently, the shortest cell cycle was found in VSMC from SHR males with the highest blood pressure. It can be concluded that gender and genotype are two independent factors participating in the control of migration and proliferation of VSMC.