Materials
MRS1523 (3-propyl-6-ethyl-5-[(ethylthio)carbonyl]-2 phenyl-4-propyl-3-pyridine carboxylate, A3R antagonist), SKF89976A hydrochloride (1-(4,4-diphenyl-3-butenyl)-3-piperidinecarboxylic acid hydrochloride, GAT-1 blocker) and non-radioactive (cold) GABA (γ-aminobutyric acid) were purchased from Sigma. Kainic acid, DPCPX (8-cyclopentyl-1,3-dipropylxanthine, A1R selective antagonist) and CPA (N6-cyclopentyladenosine, selective A1R agonist), CCPA (2-chloro-N6-cyclopentyladenosine, selective A1R agonist) and picrotoxin (GABAAR antagonist) were from Tocris (Bristol, England). Pentobarbital (Euthasol® 400 mg/mL) was from Dechra, Northwick, England). MRS5474 ((1R ,2R ,3S ,4R ,5S )-4-(2-chloro-6-((dicyclopropylmethyl)amino)-9H -purin-9-yl)bicyclo[3.1.0]hexane-2,3-diol) and MRS5698 ((1S ,2R ,3S ,4R ,5S )-4-[6-[[(3-chlorophenyl)methyl]amino]-2-[2-(3,4-difluorophenyl)ethynyl]-9H -purin-9-yl]-2,3-dihydroxy-N -methylbicyclo[3.1.0]hexane-1-carboxamide, A3R agonist) were synthesized at NIH (Jacobson group) as reported (Tosh et al., 2012a,b, 2015). CPA, CCPA, DPCPX, picrotoxin, MRS5474, MRS1523 and MRS5698 were prepared as a 5 mM stock solution in dimethyl sulfoxide (DMSO); and SKF89976A was prepared as a 50 mM stock solution in DMSO. The DMSO concentration in the working solutions did not surpass 0.01%. GABA was prepared as a 50 mM (GABA uptake) or 100 mM (GABA currents) stock solution in deionized water. The stock solutions were aliquoted and kept at -20°C until use. Fresh dilutions of these stock solutions to the final concentration were prepared for each experiment.