| Abstract: | Abstract— The uptakes of a series of methonium compounds, C2, C4, C6, C7, C8, C9 and C10, by isolated slices of rat cerebral cortex were measured. Analyses of the kinetics of uptake of C7, C8, C9 and C10 indicate that their initial influxes consist of two components. A Michaelis-Menten type uptake by carrier can account for the saturable fraction. C7 had the lowest affinity for the carrier, with values increasing for C8, C9 and C10, while C10 had the smallest maximum influx with values increasing for C9, C8 and C7. The unsaturable fraction corresponded to the slow continuous swelling of the tissue. The uptake of C8 was inhibited by other methonium compounds, choline, ACh, physostigmine, ouabain and morphine. C8 could be counter-transported by C7. There is evidence that the main driving force for uptake is the transmembrane potential, but the steric factor may be a restricting influence. |
