L-lactate transport in Ehrlich ascites-tumour cells.

摘要: Ehrlich ascites-tumour cells were investigated with regard to their stability transport L-lactate by measuring either the distribution of [ 14 C]lactate or concomitant H + ion movements. The movement lactate was dependent on pH difference across cell membrane and electroneutral, as evidenced an observed 1:1 antiport for OH - ions symport ions. 2. Kinetic experiments showed that saturable, apparent Km approx. 4.68 mM a V max. high 680 nmol/min per mg protein at 6.2 37°C. 3. Lactate exhibited temperature dependence (activation energy = 139 kJ/mol). 4. inhibited competitively (a) variety other substituted monocarboxylic acids (e.g. pyruvate, K i 6.3 mM), which themselves transported, (b) non-transportable analogues α-cyano-4-hydroxycinnamate (K 0.5 α-cyano-3-hydroxycinnamate 2mM) DL-p-hydroxyphenyl-lactate 3.6 mM) (c) thiol-group reagent mersalyl 125 muM). 5. Transport simple acids, including acetate propionate, insensitive these inhibitors; they presumably cross means different mechanism. 6. Experiments using saturating amounts “inhibitor stop” allowed measurements initial rates net influx efflux C]lactate. Influx judged be symmetrical reactions in similar concentration dependence. 7. It is concluded mediated carrier capable transporting number but not unsubstituted short-chain aliphatic acids.