EFFECTS OF 2 MICROTUBULE-DEPOLYMERIZING DRUGS, VINCRISTINE AND VINBLASTINE, ON PORPHYRIN PRODUCTION BY PRIMARY NEURAL TISSUE-CULTURES

A porphyrinogenic effect of 10(-5) to 10(-7) M Vincristine (VC) and Vinblastine (VB) was observed on primary neural tissue cultures prepared from chicken embryo brain in the presence of 10(-3) M delta-aminolevulinic acid. This effect is very pronounced in neurocyte cultures, in contrast with the documented neurite elongation defect. The microtubule disassembly by VC and VB changed the quantity of the porphyrins in the cells and medium of gial cell cultures. The correlation was studied between the depolymerization of the microtubules by VC and VB and the porphyrin overproduction of primary neural tissue cultures, the investigation also extending to 10(-7) M taxol. The direct mediation of nucleotide binding proteins of the adenyl-cyclase complex by GTP liberated from beta-tubulin during the disassembly of the microtubules is presumed.