Homo- and heteroexchange of adenine nucleotides and nucleosides in rat hippocampal slices by the nucleoside transport system

1. Here, we investigated how nucleotides and nucleosides affect the release of tritiated purines and endogenous adenosine 5′-triphosphate (ATP) from superfused rat hippocampal slices. 2. ATP elicited concentration-dependent [(3)H]purine efflux from slices preloaded with [(3)H]adenosine. High-performance liquid chromatography analysis of the effluent showed that the tritium label represented the whole set of adenine nucleotides and nucleosides, and ATP significantly increased the outflow of [(3)H]ATP. 3. Adenosine 5′-diphosphate, adenosine, uridine, uridine 5′-triphosphate, α,β-methylene-ATP and 3′-O-(4-benzoylbenzoyl)-ATP were also active in eliciting [(3)H]purine release. Adenosine (300 μM) also evoked endogenous ATP efflux from the hippocampal slices. 4. Reverse transcription-coupled-polymerase chain reaction analysis revealed that mRNAs encoding a variety of P2X and P2Y receptor proteins are expressed in the rat hippocampus. Nevertheless, neither P2 receptor (i.e. pyridoxal-5-phosphate-6-azophenyl-2′,4′-disulphonic acid, 30 μM, suramin, 300 μM and reactive blue 2, 10 μM), nor adenosine receptor (8-cyclopentyl-1,3-dipropylxanthine, 250 nM and dimethyl-1-propargylxanthine, 250 nM) antagonists modified the effect of ATP (300 μM) to evoke [(3)H]purine release. 5. The nucleoside transport inhibitors, dipyridamole (10 μM), nitrobenzylthioinosine (10 μM) and adenosine deaminase (2–10 U ml(−1)), but not the ecto-adenylate kinase inhibitor diadenosine pentaphosphate (200 μM) significantly reduced ATP-evoked [(3)H]purine efflux. 6. In summary, we found that ATP and other nucleotides and nucleosides promote the release of one another and themselves by the nucleoside transport system. This action could have relevance during physiological and pathological elevation of extracellular purine levels high enough to reverse the nucleoside transporter

Hydrogen fluoride total and partial column time series above the Jungfraujoch from long-term FTIR measurements: Impact of the line-shape model, characterization of the error budget and seasonal cycle, and comparison with satellite and model data

Time series of hydrogen fluoride (HF) total columns have been derived from ground-based Fourier transform infrared (FTIR) solar spectra recorded between March 1984 and December 2009 at the International Scientific Station of the Jungfraujoch (Swiss Alps, 46.5°N, 8.0°E, 3580 m asl) with two high resolution spectrometers (one home-made and one Bruker 120-HR). Solar spectra have been inverted with the PROFFIT 9.5 algorithm, using the optimal estimation method. An inter-comparison of HF total columns retrieved with PROFFIT and SFIT-2 – the other reference algorithm in the FTIR community - is performed for the first time. The effect of a Galatry line shape model on HF retrieved total columns and vertical profiles, on the residuals of the fits and on the error budget is also quantified. Information content analysis indicates that, in addition to HF total vertical abundance, three independent stratospheric HF partial columns can be derived from our Bruker spectra. A complete error budget has been established and indicates that the main source of systematic error is linked to HF spectroscopy and that the random error affecting our HF total columns does not exceed 2.5%. Ground-based middle and upper stratospheric HF amounts have been compared to satellite data collected by the HALOE or ACE-FTS instruments. Comparisons of our FTIR HF total and partial columns with runs performed by two 3D numerical models (SLIMCAT and KASIMA) are also included. Finally, FTIR and model HF total and partial columns time series have been analyzed to derive the main characteristics of their seasonal cycles