[3H-Thymidine autoradiographic studies on proliferation of various smooth muscle cell populations pre- and postnatally (and its possible modification) (author's transl)].

The pre- and postnatal proliferative kinetics of vascular and gastrointestinal smooth muscle cells (and possible influences on it) are reported by means of their 3-thymidine labelling indices. The 3H-autoradiographic investigations were carried out on Wistar inbred rats, strain Chbb:THOM (SPF), and on genetic osteoarthrosis mice, strain C 57 black St. Louis (in vivo investigations). The results show that the smooth muscle cells of the colon have significantly higher 3H-thymidine labelling indices than the smooth muscle cels of the other parts of the gastro-intestinal tract. Prenatally the label indices were 40 times higher than during postnatal maturation. The 3H-thymidine labelling indices (as a parameter of cell proliferation) of fetal cells of the vascular wall as well as the smooth muscle cells of the aorta during postnatal maturation are just about 10% the values of gastrointestinal smooth muscle cells at the same time. Moreover, the fetal cells of the vascular wall show 10 times higher values for the 3H-thymidine labelling index than do the smooth muscle cells of the aorta during postnatal maturation. The finding that smooth muscle cells of the vascular wall have low proliferation rates and reach a stable state later than many other populations of smooth muscle cells is discussed with regard to its theoretical and practical-therapeutical importance using kallikrein for a drug example.