Fig. 10.

Secretion of endopeptidase 3.4.24.16 by cultured astrocytes. A, Time course of endopeptidase 3.4.24.16 recovery in the medium of 15-d-old cultured astrocytes (•) and 4-d-old cultured neurons (□). Incubations were performed in PBS⁺/1% glucose, pH 7.4. At the indicated times, medium was taken off and enzymatic activity was fluorimetrically measured with QFS as detailed in Materials and Methods. Values are expressed as the percentage of whole-cell activity detectable att = 0 and are the mean ± SEM of four independent experiments. B illustrates the medium (white bars) and cellular (black bars) endopeptidase 3.4.24.16 activity in astrocytes at each time of the secretion kinetics. Values are mean ± SEM of three independent experiments. C, Western blot analysis of endopeptidase 3.4.24.16 protein content in media and cells during astrocyte-secretion experiments. Five micrograms of proteins were loaded onto an 8% SDS-PAGE and immunoblotted as described in Materials and Methods.