Entry rate kinetics of D-mannitol and carboxyl-inulin for transfer across the blood-cerebrospinal fluid barrier.
This study evaluates the entry rate kinetics of hydrophilic compounds [3H]-D-mannitol and [14C]-carboxyl-inulin across the blood-cerebrospinal fluid (CSF) barrier in a rabbit experimental model. To maintain steady state levels of these tracers in circulation, 100 microCi of [3H]-D-mannitol and 150 microCi of [14C]-carboxyl-inulin were administered as a bolus and by slow infusion for four hours via a femoral venous catheter. Entry rate kinetics of [3H]-D-mannitol and [14C]-carboxyl-inulin from plasma into cisterna magna CSF were computed using a mathematical equation described by Davson. [3H]-D-mannitol and [14C]-carboxyl-inulin maintained steady state levels throughout the experiment. Entry rates for mannitol and carboxyl-inulin were represented by a straight line, from the slope of which K(out) (or K(in)) were computed: K(in) values for mannitol and carboxyl-inulin were 0.06820 hr(-1) and 0.00023 hr(-1), respectively. Differences in the entry rate of mannitol and carboxyl-inulin may be explained by the molecular size and effective radius of these tracers.
Prockop
L D
LD
Department of Neurology, College of Medicine, University of South Florida, Tampa 33612, USA.
Naidu
K A
KA
D000818:Animals; D001812:Blood-Brain Barrier / Q000502:physiology*; D007444:Inulin / Q000031:analogs & derivatives* / Q000097:blood / Q000134:cerebrospinal fluid / Q000493:pharmacokinetics; D007700:Kinetics; D008297:Male; D008353:Mannitol / Q000097:blood / Q000134:cerebrospinal fluid / Q000493:pharmacokinetics*; D009994:Osmolar Concentration; D011817:Rabbits
D008353:Mannitol; C009737:carboxy-inulin; D007444:Inulin