Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Choroid plexuses from the lateral (LVCP) and fourth ventricles (FVCP) of rats or rabbits were incubated in artificial cerebrospinal fluid (CSF) containing 1 microM [14C]L-carnitine with various concentrations of L-carnitine ranging from 0.01 mM to 1.0 mM. The time course of 1 microM [14C]L-carnitine uptake by the choroid plexus indicated that it increased linearly for the first 15 min. Steady-state levels were reached by 30 min with tissue concentrations more than 20 (FVCP)- to 30 (LVCP)-fold greater than the concentration in the medium. The uptake of [14C]L-carnitine was increased with increasing concentrations of the substrate in the medium and this uptake followed Michaelis-Menten kinetics. The uptake by the rat choroid plexus took place against a concentration gradient via a saturable process and kinetic analysis revealed Km of 32 microM (LVCP) and 34 microM (FVCP) and Vmax of 21 (LVCP) and 17 nmol/ml/min (FVCP), respectively. Ouabain inhibited the uptake by 51% (FVCP) and 48% (LVCP) and hypothermia (0 degrees C) produced inhibition by 97% (FVCP) and 96% (LVCP), respectively. However, the uptake of L-carnitine was not sensitive to probenecid or tyrosine, which indicates the presence of an independent carrier for L-carnitine in the choroid plexus. Similar results were obtained with the rabbit choroid plexus.
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PMID:Kinetic analysis of L-carnitine uptake by the choroid plexus. 193