Studies on the transport of carnitine in the brain using synaptosomes isolated from guinea-pig cerebral cortex.
Synaptosomes isolated from guinea pig cerebral cortex accumulate L-carnitine from the medium in an active process, dependent on the sodium gradient across the plasma membrane and on (Na+ + K+)-ATPase activity. L-Carnitine uptake is inhibited by oxidative phosphorylation uncouplers and by ouabain, a known inhibitor of (Na+ + K+)-ATPase. In addition, the omission of Na+ or its replacement by Li+ inhibited the transport, which was also competitively inhibited by gamma-aminobutyrate. The kinetics of carnitine uptake show that the overall process would consist of two components: a passive diffusion and a carrier-mediated transport which is saturated at 1-2 mM carnitine concentration.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002331:Carnitine / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism*; D006168:Guinea Pigs; D007700:Kinetics; D008094:Lithium / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D005680:gamma-Aminobutyric Acid; D008094:Lithium; D000254:Sodium-Potassium-Exchanging ATPase; D002331:Carnitine