Increased serum mitogenic activity for arterial smooth muscle cells associated with relaxation and low educational level in human subjects with high but not low hostility traits: implications for atherogenesis.

Proliferation of arterial smooth muscle cells (aSMC) is a key component of atherogenesis. A sample of 225 volunteers, aged 21-65 years, was exposed to "frustration," "harassment," or "relaxation," after completing the 50-item Hostility subscale of the Minnesota Multiphasic Personality Inventory (MMPI). Whole blood was measured before and after exposure for platelet-derived growth factor (PDGF), and sera were evaluated for total and HDL cholesterol concentrations and PDGF-independent mitogenic activity (SMA). Blood pressure and pulse rate were also evaluated. Analyses of SMA (i.e., serum independent of PDGF) revealed an increase in mitogenic effect for cultured human aSMC when hostility was treated as a dichotomous modifier. Among high-hostility subjects, surprisingly, those in the relaxed group and those with a lower educational level were found to have a significant mitogen response; no significant effects were observed for the low-hostility groups. The data suggest that endogenous stresses may occur in high-hostility individuals when "relaxed," to influence proliferation of arterial smooth muscle cells, as a contribution to atherogenesis. In individuals with lower educational levels and higher hostility scores, lifestyle changes may play a role.