Fig. 4: The flux of inositol across the plasma membrane and the effect of drugs.

a, c Neurons were treated with either 1 mM lithium or 3 μM FLUO for 20 h before extraction, and also labelled with ³H-inositol for the last 1 h. Some neurons were also stimulated with carbachol (1 mM) during the 1-h labelling period. The histograms show the cpm/well in extracts of the cytosol (light grey bars) and extracts of membranes from the same neurons (dark grey bars). Data are means ± SEM, n = 4. Data in (a–b) and (c–d) are from two separate platings and each experiment was repeated with similar results. For comparison of influx and efflux, the white bar shows the efflux from control neurons as shown in (b) and (d) but plotted on the same scale as the cytosol and lipid. b, d Neurons were labelled to steady-state for 5 days (D6–11) with ³H-inositol and treated with either 1 mM lithium or 3 μM FLUO for the last 20 h before washing away the radioactivity, re-feeding the neurons with media and drugs, and returning the neurons to the CO₂ incubator for 1 h. Some neurons were also stimulated with carbachol (1 mM) during the 1-h incubation. The white bars show the amount of inositol present in the collected media after 1 h. The light grey bars show the amount remaining in the cytosol (acid extraction) of the same neurons. Data are means ± SEM, n = 4