DL-Carnitine-d9 is intended for use as an internal standard for the quantification of carnitine by GC- or LC-MS. DL-Carnitine is a racemic mixture of L- and D-carnitine. Unlike L-carnitine, DL-carnitine (60 and 120 µM) does not increase glucose or urea production from L-glutamine in isolated rat liver and does not compensate for carnitine deficiency in the skeletal muscle of rats receiving a carnitine-deficient diet.1,2 DL-Carnitine induces tetanic fade in stimulated isolated rat phrenic nerve diaphragm preparations when used at a concentration of 60 µM, an effect that can be blocked by choline.3
1.Lopes, G., Gazola, V.A., Galende, S.B., et al.Comparative acute effects of l-carnitine and dl-carnitine on hepatic catabolism of l-alanine and l-glutamine in ratsActa Pharmacol. Sin.25(10)1257-1261(2004) 2.Spasov, A.A., Iezhitsa, I.N., Kravchenko, M.S., et al.Effects of L-, D-, and DL-carnitine on morphometric parameters of skeletal muscle and exercise performance of laboratory animals receiving carnitine-deficient dietBull. Exp. Biol. Med.142(4)458-460(2006) 3.Lopes, G., Bazotte, R.B., Curi, R., et al.L- and DL-carnitine induce tetanic fade in rat neuromuscular preparationBraz. J. Med. Biol. Res.36(9)1255-1262(2003)