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Primary cultures of cells from late pregnant rat myometrium contain B2 kinin receptors through which bradykinin (BK) stimulates inositol phosphate (InsP) formation and arachidonic acid (20:4) release. Equilibrium binding at 4°C revealed that [34H]BK identified a maximal number of cell surface B2 kinin receptor binding sites on rat myometrial cells of 308 ± 78 fmol/106 cells with apparently a singl

This study was undertaken to evaluate the role of internalization in the action of the peptide autacoid bradykinin (BK). At 4°C [3H]BK binds to an apparently single class of B2 kinin receptors on DDT1 MF-2 smooth muscle cells (C. M. Munoz, S. Cotecchia, and L. M. F. Leeb-Lundberg, manuscript submitted). At this temperature the [3H]BK binding was confined exclusively to the cell surface. On the oth

We have previously reported that [3H]bradykinin ([3H]BK) identifies high- and low-affinity B2 kinin receptor sites in bovine myometrial membranes which are sensitive and insensitive respectively to guanine nucleotides. Here we show that these receptor-binding sites are solubilized by the detergent CHAPS. Equilibrium binding in soluble preparations revealed that [3H]BK identified a maximal number o

We have examined the effect of bradykinin (BK) and other peptide mediators with related cellular actions on tyrosine phosphorylation in confluent Swiss 3T3 fibroblast cells using an anti-phosphotyrosine antibody. Immunoblots of extracts from cells stimulated with BK showed a major heterogeneous band centered at Mr 120,000. Three phosphorylated protein species were present within this band. The low

Barbiturates and the related depressant drugs, etazolate and etomidate, inhibited both the binding of [3H]bicuculline methochloride (BMC) to γ-aminobutyric acid (GABA) receptor sites and the binding of [3H]β-carboline-3-carboxylic acid methyl ester (βCCM) to benzodiazepine receptor sites in mammalian brain. These concentration-dependent effects were chemically specific and stereospecific in a mann

γ-Aminobutyric acid (GABA) increases the rate of 36Cl- efflux from preloaded rat hippocampal slices in a dose-dependent manner (EC50: 400 μM). This action has the pharmacological specificity expected of activation of GABA receptor in that it is mimicked by the agonists muscimol and 3-aminopropanesulfonic acid, and blocked by the antagonists bicuculline and picrotoxinin. GABA uptake inhibitors, nip

A novel high affinity radioiodinated photoaffinity probe, 4-amino-6,7-dimethoxy-2[4-[5(3-[125I]iodo-4-azidophenyl)pentanoyl]-1-piperazinyl]- quinazoline, structurally related to the potent α1-adrenergic antagonist prazosin, was developed and used to covalently label the rat cerebral cortex α1-adrenergic receptor. In the absence of light, this ligand binds to cortex plasma membranes with a dissocia

Benzodiazepine receptor binding heterogeneity evident from differential affinities of some ligands was compared with that suggested by differential interactions with γ-aminobutyric acid (GABA)/bicuculline and pyrazolopyridine/barbiturate receptor sites. The GABA receptor antagonist bicuculline only partially reverses pentobarbital enhancement of [3H] diazepam binding in rat brain membranes, while

Numerous barbiturates, such as (±)-pentobarbital, reversibly enhance the affinity for equilibrium binding of [3H]diazepam to well-washed rat cortical membranes in a chloride-dependent and picrotoxinin-sensitive manner [Leeb-Lundberg et al., Proc. Natl. Acad. Sci. U.S.A. 77:7468-7472 (1980)]. The chemical specificity and stereospecificity of this barbiturate effect in vitro has been examined in det

The two pyrazolopyridines, etazolate (SQ20009) and cartazolate (SQ65396), enhance the binding of [3H]diazepam to benzodiazepine receptor sites in rat brain. This enhancement is due to a change in affinity without a change in maximal binding. Pentobarbital also enhances [3H]diazepam binding by lowering the K(D). Pentobarbital gives a maximal enhancement of benzodiazepine binding slightly greater th

The specific binding of [3H]α-dihydropicrotoxinin to rat brain membranes was inhibited competitively and potently (IC50 ≅ 100 nM) by a convulsant benzodiazepine drug, RO5-3663. This compound did not inhibit high affinity flunitrazepam binding to the same tissue under similar conditions, and its reported pharmacological activity as an antagonist of GABAergic synaptic transmission, which resembles t

Unlike the anesthetic barbiturate pentobarbital and the anxiolytic pyrazolopyridine etazolate, which enhance [3H]diazepam binding to rat brain membranes, the anticonvulsant barbiturates phenobarbital and metharbital, and also chlormethiazole, at therapeutic concentrations (10-1000 μM), do not stimulate [3H]diazepam binding, but instead block the enhancement by both pentobarbital and etazolate. The

Barbiturates enhance the binding of [3H]diazepam to benzodiazepine receptor sites in rat brain. This effect occurs at pharmacologically relevant concentrations of barbiturates, and the relative activity of a series of compounds correlates highly with anesthetic activity of the barbiturates and with their ability to enhance postsynaptic inhibitory responses to the neurotransmitter γ-aminobutyric ac

(3H)α-Dihydropicrotoxinin (DHP) binds to membrane sites in mammalian brain which appear to be related to the convulsant action of picrotoxin at the level of membrane Cl-channels which are at least partially regulated by the inhibitory neurotransmitter GABA. DHP binding to rat cerebral cortex (assayed by centrifugation) showed a single class of sites (Kd = 2μM) and Bmax of 4 pmol/mg protein, and wa