The objective of this work was to isolate cultured mouse cells with amplified adenosine deaminase genes. Such cell lines should be very useful in an effort to obtain the protein and nucleic acid probes required to study adenosine deaminase gene structure and regulation. Since adenosine deaminase expression is not required for growth of cells in culture, the first step necessary to isolate adeno...

Although the purine adenosine acts as an extracellular neuromodulator in the mammalian CNS in both normal and pathological conditions and regulates sleep, the regulation of extracellular adenosine in the day and night is incompletely understood. To determine how extracellular adenosine is regulated, rabbit neural retinas were maintained by superfusion at different times of the regular light/dar...

The adenosine kinase enzymes from arabinofuranosyladenine-resistant (araAr) mutants of the baby hamster kidney cell line were analyzed using adenosine kinase-specific antibody probes purified by adenosine kinase-Sepharose column chromatography. Wild-type baby hamster kidney cells were shown to produce two adenosine kinase polypeptides of Mr 43,000 and 40,000. The class I araAr mutants that have...

ceeds supply.@ Adenosine measurement is difficult in any given circumstance, as elements such as endothe hal cell and blood uptake and release, interstitial concentration, intracellular binding with SAH-hydro lase, and flow all influence venous adenosine concen trations. Adenosine is removed from tissues either by phos phorylation to AMP by adenosine kinase or by deam ination by adenosine deami...

Adenosine is a potent neuromodulator in the CNS, but the mechanisms that regulate adenosine concentrations in the extracellular space remain unclear. The present study demonstrates that increasing the intracellular concentration of adenosine in a single hippocampal CA1 pyramidal neuron selectively inhibits the excitatory postsynaptic potentials in that cell. Loading neurons with high concentrat...

S-Adenosylhomocysteine (SAH) hydrolase was purified 25-fold from bakers' yeast by chemical methods and column chromatography. The purified enzyme could readily synthesize SAH from adenosine and homocysteine, but could hydrolyze only negligible amounts of SAH. The purified enzyme showed no activity towards S-adenosylmethionine, methylthioadenosine, or adenosine. Several nucleotides, sulfhydryl c...

The intracellular flux rate through adenosine kinase (adenosine-->AMP) in the well-oxygenated heart was investigated, and the relation of the AMP-adenosine metabolic cycle (AMP<-->adenosine) to transmethylation (S-adenosylhomocysteine [SAH]-->adenosine) and coronary flow was determined. Adenosine kinase was blocked in isolated guinea pig hearts by infusion of iodotubercidin in the presence of t...