[On the effect of biologically active substances (experimental studies) (author's transl)]

The influence of prolonged Procaine and Turigeran therapy on the cellular kinetics of the mucous membrane of the liver and small intestine has been studied by means of 3H-thymidine histo-autoradiography of a total of 240 12-month-old male Wistar rats. The following observations have been made: 1. The pool of DNA-synthesizing liver parenchyma cells and Kupffer's cells in the treated animals is clearly increased compared with that of the untreated controls. There is no difference between the rats treated with Procaine and those treated with Turigeran. 2. Nor does the cellular kinetics of the mucosa of the small intestine exhibit any differences between the animals treated with Procaine and those treated with Turigeran. Since, on the other hand, significant differences appear between the treated animals and the untreated controls regarding all characteristics of cellular kinetics, this effect is solely attributable to Procaine. 3. The various phases of the cellular cycle are prolonged in the treated animals, resulting in an overall delay in the generative cycle. 4. A reduced speed of migration of the cells in the region of crypts and villi finally results in the fact that in spite of the reduced rates of proliferation a greater number of labelled cells can be observed in the crypts of the treated animals (labelling index). 5. The unmitigated effect of Procaine is discernible for at least two weeks after the discontinuation of the treatment.