Tissue carnitine fluxes in vitamin C depleted-repleted guinea pigs

The biosynthesis of carnitine requires vitamin C as a cofactor for two sepa rate hydroxylation steps. The majority of body carnitine (approximately 98% ) is located in muscle and less than 0.5% is present in plasma. We examined the physiologic dynamics of plasma free carnitine and muscle total acid-so luble carnitine in vitamin C-depleted guinea pigs repleted with increasing amounts of vitamin C. Animals were fed a vitamin C-deficient diet for 3 wee ks at which time symptoms of scurvy were evident. Animals were repleted wit h increasing doses of vitamin C, from 0.5 to 10.0 mg vitamin C/100 g body w eight daily. Muscle total acid-soluble carnitine concentrations tended to c orrelate directly with plasma vitamin C (r = 0.41, P = 0.087) during the re pletion phase of the study. Conversely, plasma free carnitine was inversely related to liver vitamin C (r = -0.54, P = 0.020) and to muscle total acid -soluble carnitine (r = -0.56, P = 0.015). Mean plasma free carnitine value s fell 30% over the course of vitamin C repletion (P > 0.05) and mean muscl e total acid-soluble carnitine rose by 30% (P > 0.05), These data suggest t hat elevated plasma free carnitine may indicate a low to marginal vitamin C status. (C) Elsevier Science Inc. 1999. All rights reserved.