SEX-DEPENDENT DIFFERENCES IN GROWTH AND MORPHOLOGY OF CULTURED VASCULAR SMOOTH-MUSCLE CELLS FROM NEWBORN RATS

The morphology and proliferation of vascular smooth muscle cells (VSMC ) were studied in cultures prepared from the aorta of newborn male and female Wistar rats. The doubling times (DT) of the male-derived popul ation were 16.4 +/- 0.7 h and 30.0 +/- 2.2 h in the exponential and po st-exponential growth phases, respectively. In the female donor cells, the corresponding DT values were significantly longer, i.e. 21.9 +/- 1.8 h and 38.0 +/- 2.2 h. In addition, the period of growth was shorte r in the female-derived cultures. The percentage of H-3-thymidine labe lled cells in male cultures was 61.0 +/- 3.1, 92.8 +/- 1.9 and 98.7 +/ - 0.6% at 2, 27 and 52 h, respectively. In the female-derived populati ons, only 24.6 +/- 4.4, 66.1 +/- 3.8 and 82.8 +/- 2.0% of cells were l abelled at the corresponding incubation intervals. As a consequence, t he final population density in male cultures was 5.6 times higher. In addition, the male-derived VSMC were mainly spindle-shaped and bulgy i n appearance while those from female donors were flat and polygonal wh ich means that the cells were adhering to the growth support to a diff erent extent. The study revealed early determination and long-term per sistence of lower adhesiveness as well as higher growth potential of m ale VSMC, i.e. properties which may be of importance for explaining th e higher incidence of vascular wall disorders in males.