Kinetic analysis of L-leucine transport across the blood-brain barrier.
Unidirectional L-leucine influx across cerebral capillaries was measured at different concentrations with an in situ rat brain perfusion technique, which has several advantages over presently-used methods such as the Brain Uptake Index (BUI) technique. The maximal influx rate (Vmax) and half-saturation concentration (Km) equaled 1.07 +/- 0.02 X 10(-3) mumol X s-1 X g-1 and 0.026 +/- 0.002 mumol X ml-1, respectively, for the saturable component, and the constant for non-saturable influx equaled 6.8 +/- 1.4 X 10(-5) s-1. These values differ by 3-4-fold from respective values obtained with the BUI technique.
D000818:Animals; D001812:Blood-Brain Barrier; D001921:Brain / Q000378:metabolism; D002196:Capillaries / Q000502:physiology; D002250:Carbon Radioisotopes; D007444:Inulin; D007700:Kinetics; D007930:Leucine / Q000378:metabolism*; D008297:Male; D008433:Mathematics; D008959:Models, Neurological; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D014316:Tritium
D002250:Carbon Radioisotopes; D014316:Tritium; D007444:Inulin; D007930:Leucine