title: The efflux of purine nucleobases and nucleosides from the rat brain.
abstract: The efflux of purine nucleobases and their nucleosides from the rat brain was investigated using the brain efflux index (BEI) method. Calculated BEI values showed that purine nucleobases had very rapid initial efflux after the intracerebral injection, which was followed by the slower efflux due to the intracellular trapping of labelled molecules and confirmed by the capillary depletion technique. The efflux of ribonucleosides was much slower than the efflux of nucleobases and the structure of the sugar moiety seemed to be important, since a significant difference in the efflux velocity between ribo- and deoxyribonucleosides was observed. The results of self- and cross-inhibition studies suggested that the efflux of test molecules was saturable and that purines shared the same transport system on the abluminal side of the blood-brain barrier.
authors.affiliation: Institute of Biochemistry, School of Medicine, Belgrade, Yugoslavia.
authors.forename: Aleksandra J
authors.initials: AJ
authors.lastname: Isakovic
authors.forename: Malcolm B
authors.initials: MB
authors.lastname: Segal
authors.forename: Bogdan A
authors.initials: BA
authors.lastname: Milojkovic
authors.forename: Mirjana P
authors.initials: MP
authors.lastname: Dacevic
authors.forename: Sonja T
authors.initials: ST
authors.lastname: Misirlic
authors.forename: Miodrag L
authors.initials: ML
authors.lastname: Rakic
authors.forename: Zoran B
authors.initials: ZB
authors.lastname: Redzic
mesh_terms: D000241:Adenosine / Q000097:blood / Q000134:cerebrospinal fluid; D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects* / Q000502:physiology; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002250:Carbon Radioisotopes / Q000378:metabolism; D002352:Carrier Proteins / Q000187:drug effects* / Q000502:physiology; D003853:Deoxyribonucleosides / Q000097:blood / Q000134:cerebrospinal fluid; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D006151:Guanosine / Q000097:blood / Q000134:cerebrospinal fluid; D019271:Hypoxanthine / Q000097:blood / Q000134:cerebrospinal fluid; D007276:Injections, Intraventricular; D007288:Inosine / Q000097:blood / Q000134:cerebrospinal fluid; D011684:Purine Nucleosides / Q000097:blood / Q000134:cerebrospinal fluid / Q000378:metabolism*; D011687:Purines / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D002250:Carbon Radioisotopes; D002352:Carrier Proteins; D003853:Deoxyribonucleosides; D011684:Purine Nucleosides; D011687:Purines; D006151:Guanosine; D019271:Hypoxanthine; D007288:Inosine; D000241:Adenosine