Daniel Guo
Quae Chong1, Jean-Marc Nuoffer2, Christine Sandra
Bolliger1, Peter Vermathen1, Chris Boesch1,
Roland Kreis1
1Department of Clinical Research, University
Bern, Bern, Switzerland; 2Departement Hmatologie, Onkologie,
Infektiologie, Labor-Medizin und Spitalpharmazie (DOLS), Inselspital, Bern,
Switzerland
Normal
human blood and brain histidine concentrations were measured over a 10 hour
period after an oral load. On average, blood histidine concentrations reached
a maximum of 3.5 mM while brain histidine peaked at 1.9 mM, 5 hours after
blood. Applying the symmetric Michaelis-Menten kinetics resulted in kinetic
parameters of maximum transport of 23 nmol/g/min, an apparent Michaelis
constant of 2.1 mM and a cerebral metabolization rate of 0.3 nmol/g/min. The
complexity of the system investigated and various factors render the data
inconclusive upon the appropriate kinetic model and potential subject dependence
of the kinetics.