guanosine-triphosphate and 1-10-phenanthroline

It has been found that Tb(3+) can react with guanosine-5'-triphosphate (GTP) and o-phenanthroline (phen), resulting in the intrinsic fluorescence of Tb(3+). This fluorescence can be enhanced by adding La(3+), Gd(3+), Lu(3+), Sc(3+), Y(3+), and so on, among which Gd(3+) produces the greatest enhancement. These are new co-luminescence systems. The experiments indicate under optimum conditions, the fluorescence intensity of the Tb-Gd-GTP-phen system is proportional to the concentration of GTP over the range 1x10(-9) to 3x10(-5) mol/l. The detection limit is 3.1x10(-10) mol/l. The proposed method provides the most sensitive fluorimetry of GTP so far. The mechanism of the Tb-Gd-GTP-phen system has also been studied. The data indicates that there is a large congeries of Tb-Gd-GTP-phen, and the fluorescence enhancement of the Tb-Gd-GTP-phen system is considered to originate from intramolecular and intermocular energy transfers, and the energy-insulating sheath of the Gd complex.

Topics: Gadolinium; Guanosine Triphosphate; Organometallic Compounds; Phenanthrolines; Sensitivity and Specificity; Spectrometry, Fluorescence; Terbium

The characteristics of dopamine (DA) D2 receptors were studied in rat hippocampus and for comparison in striatum using the [3H]spiperone radioreceptor assay in vitro. D2 receptors exhibit a bimodal distribution along the length of the hippocampus. Heterogeneity also exists in the transverse axis with high densities in the molecular layers of the subiculum and CA1 plus CA2. As in the striatum, D2 receptors in both dorsal and ventral hippocampus display high and low affinity states for agonists, but all three regions differ with regard to the percentage of receptors in these states. The modulation of these affinity states by GTP, Mg2+ and the iron-chelator, 1,1-O-phenanthroline, differs markedly between dorsal and ventral hippocampus, and between these regions and the striatum. A new model for the modulation of the affinity of D2 receptors for agonists is presented. These data suggest the presence of regional differences in the composition of the D2 receptor-regulatory protein complex.

Topics: Animals; Corpus Striatum; Guanosine Triphosphate; Hippocampus; In Vitro Techniques; Iron Chelating Agents; Magnesium; Male; Phenanthrolines; Radioligand Assay; Rats; Rats, Inbred Strains; Receptors, Dopamine D2; Spiperone