Carnitine transport in rat heart slices: II. The carnitine/deoxycarnitine antiport.
In rat heart slices carnitine transport occurs in an exchange process with deoxycarnitine. This has been demonstrated in double labelling experiments allowing a preloading of either 3H-carnitine or 14C-deoxycarnitine, the immediated precursor of carnitine. The stoichiometry of the carnitine/deoxycarnitine exchange resulted close to one in both directions. The relative kinetics supports the assumption that the process is mediated by a membrane bound protein. The results may rationalize the circumstance that carnitine is taken up by myocardium against a concentration gradient. The meaning of the carnitine/deoxycarnitine exchange is discussed.
D000818:Animals; D017920:Antiporters; D001622:Betaine / Q000031:analogs & derivatives / Q000378:metabolism; D002250:Carbon Radioisotopes; D002331:Carnitine / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014316:Tritium
D017920:Antiporters; D002250:Carbon Radioisotopes; D002352:Carrier Proteins; C049118:carnitine-deoxycarnitine antiport; D014316:Tritium; D001622:Betaine; C002889:gamma-butyrobetaine; D002331:Carnitine