alpha-[3H]Dihydropicrotoxinin (DHP) and [3H]diazepam binding proteins were solubilized from rat brain membranes with 1% Lubrol-Px. Gel filtration of the Lubrol-solubilized fraction revealed that [3H]DHP and [3H]diazepam bind to two distinct peaks with apparent molecular weights of 185,000 and 61,000, respectively. The signal-to-noise ratio of [3H]DHP binding to 185,000-dalton fractions was impr...

A method for the preparation of biologically active [3H]- and [13C]bleomycin A2 is described. Demethyl Cu(II):bleomycin A2, isolated after pyrolysis of Cu(II):bleomycin A2, was methylated with either [3H]-or [13C]methyl iodide, which resulted in Cu(II):bleomycin A2 labeled in the dimethylsulfonium moiety. Copper was removed by treatment with dithizone in chloroform, and structures were verified...

N6-Cyclohexyl[3H]adenosine ([3H]CHA) and 1,3-diethyl-8-[3H]phenylxanthine ([3H]DPX) to bind to adenosine receptors in brain membranes. The agonist [3H]CHA has high affinity in both bovine and guinea pig brain (Kd, 0.7 nM and 6 nM, respectively). [3H]CHA binding kinetics are slow (dissociation t1/2;60 min); binding is much higher at 25 degrees C than at 0 degrees C and is inhibited by guanine nu...

Studies of the reversible binding of [3H]cortisol by rat gastrocnemius muscle cytoplasm in vitro reveal specific binding in the 27,000 times g supernatant fraction at 0 degrees. The [3H]cortisol-binding molecule had an apparant Kd value of 1.7 times 10-7 M and the number of binding sites was 0.99 pmol per mg of cytosol protein. Only a single class of [3H]cortisol-binding sites could be detected...

Binding sites for [3H]muscimol, an analogue of gamma-aminobutyric acid (GABA) were localized in the synaptic layers of chicken retina by light microscopic and electron microscopic autoradiography. Light microscopic autoradiography of cryostat sections incubated in [3H]muscimol or [3H]GABA revealed identical binding patterns: a band over the inner plexiform layer (IPL) and a band over the outer ...

Addition of platelet-activating factor (PAF) to cells doubly labeled with [14C]glycerol plus [3H]arachidonic acid resulted in a transient decrease of [14C]glycerol-labeled phosphatidylinositol (PI) and a transient increase of [14C]glycerol-labeled lysophosphatidylinositol (LPI). [3H]Arachidonate-labeled PI, on the other hand, decreased in a time-dependent manner. The radioactivity in phosphatid...

[3H]MK-801 binding in rat brain was characterized using a quantitative autoradiographic binding assay. [3H]MK-801 binding (5 nM) reached equilibrium by 120 min at 23 degrees C. [3H]MK-801 appeared to label a single high affinity site with an affinity constant of approximately 11 nM. [3H]MK-801 binding was heterogeneously distributed throughout the brain with the following order of binding densi...

The role of catecholamines (CAs) in cat carotid body chemoreception has been controversial. On the basis of pharmacological experiments, it would appear that endogenous dopamine (DA) may act either as an inhibitory or excitatory transmitter. Neurochemical studies on the effects of natural stimulation on the release of carotid body CAs in the cat have also been inconclusive. In the present study...

[3H]pseudomorphine (3H-PM) was prepared by the oxidation of [3H]morphine. A method for the estimation of 3H-PM in biological materials was developed with a minima1 sensitivity of 2.5 ng/ml of biologic material. Following the subcutaneous injection of 3H-PM (10 mg/kg as free base) in rats, the levels of 3H-PM in brain and spinal cord over a 2-hr period ranged between 46 to 17.9 rig/g and 24 to 7...

Entomologists have used a range of techniques to treat insects with neuroactive compounds, but it is not always clear whether different treatment methods are equally effective in delivering a compound to a target organ. Here, we used five different techniques to treat honeybees with 3H-octopamine (3H-OA), and analysed the distribution of the 3H radiolabelled compound within different tissues an...