1. Alkaloids vincristine and vinblastine are used as chemotherapeutic agent in the treatment of many cancer types

2. Complete remissions were obtained in 50% of metastasising seminoma with a combination chemotherapy consisting of Cyclophosphamide, Vinblastine and Amethopterin.

3. Normal rats and rats treated with the mt poisons colchicine or vinblastine or with the acidotropic agent chloroquine (Cq) were used.

4. In metastasising teratocarcinoma of the testis 42% remissions — 4% complete remissions, 38% partial remissions — were observed with a combination of Actinomycin D, Cyclophosphamide, Vinblastine and Amethopterin.

5. Guinea pigs were treated with moderately to highly toxic doses of cyclophosphamide, triethylene melamine, ibenzmethyzine, 6-mercaptopurine, amethopterin, actinomycin C, vinblastine, podophyllin derivative and prednisolon for 10–14 days.

6. The lymphatic tissues were damaged by all these drugs, the granulopoiesis by all substances exept by amethopterin and prednisolone, the erythropoiesis, however, only by TEM, actinomycin C, vinblastine and by large doses of amethopterin.

7. Methods Using the HCT-8 intestinal adenocarcinoma cell monolayer model we assessed P-Gp-mediated, transmembrane, secretory transport of vinblastine (3H-VIN), a P-Gp substrate, as well as the cell-associated VIN-content in presence/absence of above chemomodulators under different extracellular pH (pHo) conditions known to prevail in carcinoma.