title: Striatal adenosine levels measured 'in vivo' by microdialysis in rats with unilateral dopamine denervation.
abstract: Adenosine, inosine, hypoxanthine and guanosine were measured in perfusates collected from the right and left striatum of halothane-anaesthetized naive and 6-hydroxydopamine-denervated rats by using microdialysis. Samples were taken under basal and KCl-stimulated conditions. Dopamine, dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were simultaneously measured. Purines and monoamines were assayed by HPLC-UV and HPLC-EC respectively. In naive rats, basal adenosine (1 microM), inosine (2 microM), hypoxanthine (4 microM), guanosine (0.5 microM) and dopamine (DA, 0.02 microM) levels (corrected by using the in vitro % recovery of each probe) were increased by the inclusion of 100 mM of KCl into the perfusion medium (2.5-, 3-, 3.5-, 1.5- and 30-fold, respectively, while DOPAC (6 microM), HVA (5 microM) and 5-HIAA (3 microM) levels were (72%, 68% and 45% respectively). DA was strongly diminished in the denervated striatum, but when detectable, could be increased (1- to 12-fold) by KCl stimulation. Adenosine, inosine, hypoxanthine and guanosine were, however, largely unaffected by the DA denervation and could be enhanced by KCl stimulation (2-, 3-, 4- and 1.5-fold respectively). The present results indicate that: (1) as in the case for DA, there is a pool of striatal adenosine which is releasable by high concentrations of extracellular K+; however, (2) this pool of adenosine seems not to be significantly modified by mesencephalic dopamine deafferentation.
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000032:analysis; D000241:Adenosine / Q000032:analysis*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003342:Corpus Striatum / Q000032:analysis* / Q000187:drug effects; D003714:Denervation; D003956:Dialysis / Q000379:methods; D004298:Dopamine / Q000032:analysis; D006151:Guanosine / Q000032:analysis; D006719:Homovanillic Acid / Q000032:analysis; D006892:Hydroxydopamines / Q000494:pharmacology; D006897:Hydroxyindoleacetic Acid / Q000032:analysis; D019271:Hypoxanthine; D007042:Hypoxanthines / Q000032:analysis; D007288:Inosine / Q000032:analysis; D008297:Male; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D006892:Hydroxydopamines; D007042:Hypoxanthines; D015102:3,4-Dihydroxyphenylacetic Acid; D006151:Guanosine; D019271:Hypoxanthine; D006897:Hydroxyindoleacetic Acid; D007288:Inosine; D016627:Oxidopamine; D000241:Adenosine; D004298:Dopamine; D006719:Homovanillic Acid