Pulmonary pharmacology of a novel, smooth muscle-selective muscarinic antagonist in vivo.

The need for a smooth muscle-selective muscarinic antagonist that could provide oral bronchodilator activity with minimal side effects has led to the discovery of 3-(4-benzyl-piperazinyl)-1-cyclobutyl-1-hydroxy-1-phenyl-2-propanone (NPC-14695). Orally administered NPC-14695 was as potent as albuterol in the prevention of aerosolized carbachol-induced collapse in conscious guinea pigs. After s.

The role of receptor binding in drug discovery.

Radioligand receptor binding has been used extensively to identify and characterize a host of receptors and enzymes targeting virtually every therapeutic area. Many drug discovery programs have been based on the utilization of radioligand receptor binding technology to identify lead compounds which interact with receptors likely to be important in neuronal, immunological, gastrointestinal, and cardiovascular function/dysfunction. There are several obvious advantages to using in vitro receptor binding as a first level screen when compared to in vivo pharmacometric screens.

2-Phenyl-3H-imidazo[4,5-b]pyridine-3-acetamides as non-benzodiazepine anticonvulsants and anxiolytics.

A series of 2-phenyl-3H-imidazo[4,5-b]pyridine-3-acetamides were designed and synthesized as non-benzodiazepine anxiolytics based on a molecular disconnection of a typical 1,4-benzodiazepine (BZD). A number of these compounds showed submicromolar potency in a [3H]benzodiazepine binding assay in vitro and good potency in protecting rodents against pentylenetetrazole-induced seizures. Compound 84 appears to be a selective anticonvulsant (pentylenetetrazole) agent when tested against a profile of chemically and electrically induced seizures in mice.

Mechanism for the emetic side effect of xanthine bronchodilators.

The usefulness of xanthine bronchodilators in the treatment of asthma is often limited by the side effects of nausea and vomiting. We investigated the mechanism of emesis induced by xanthines, by examining the roles of phosphodiesterase (PDE) inhibition and adenosine antagonism. Theophylline, enprofylline, 8-phenyltheophylline and isobutylmethylxanthine (IBMX), as well as vehicle, were given to ferrets at doses ranging from 0.

Muscarinic receptors: relationships among phosphoinositide breakdown, adenylate cyclase inhibition, in vitro detrusor muscle contractions and in vivo cystometrogram studies in guinea pig bladder.

The relationships between activation of muscarinic receptors in guinea pig bladder measured as carbachol-stimulated inositol phosphate (IP) accumulation, oxotremorine-induced adenylate cyclase (AC) inhibition and bladder detrusor smooth muscle contraction determined in vitro as well as in vivo in the slow filling cystometrogram (CMG), were analyzed from the potencies of a number of muscarinic antagonists to block these responses. Significant positive linear correlations were found among the inhibitory potencies of 10 muscarinic antagonists to inhibit phosphoinositide (PI) turnover and both detrusor muscle contraction in vitro, as well as peak intravesical bladder pressure in vivo in the CMG (r = 0.8, P less than .

Selective agents for muscarinic receptors linked to phosphoinositide breakdown.

We examined the effects of several muscarinic agonists and antagonists on phosphoinositide breakdown (PI) and adenylate cyclase (AC) inhibition in rat cerebral cortex and heart, respectively. Acetylcholine, carbachol and methacholine behaved as full agonists in both systems. In contrast, oxotremorine and arecoline failed to stimulate PI turnover but were potent and efficacious at inhibiting AC.

Affinity and selectivity of the optical isomers of 3-quinuclidinyl benzilate and related muscarinic antagonists.

All of the optical isomers of the muscarinic antagonists 3-(1-azabicyclo[2.2.2]octyl) alpha-hydroxy-alpha,alpha-diphenylacetate (3-quinuclidinyl benzilate, QNB, 1) 3-(1-azabicyclo[2.

Heterologous up-regulation of Ni-coupled receptors in cultured neural hybrid cells by a transferable factor, whose expression is inhibited in a cyclic AMP-dependent, cell-specific manner.

Opiate, muscarinic, and alpha 2-adrenergic receptors on NCB-20 and NG108-15 neuroblastoma hybrid cells were up-regulated by treatment of the cells with media (CM) conditioned by previous incubation with either cell type. NG cells treated with CM from both NCB and NG cells (NCB-CM or NG-CM) showed a 2-fold increase in opiate receptor density relative to untreated cells, with no change in ligand affinities. Opiate receptor density on NG cells was also enhanced approximately 2-fold by CM derived from dibutyryl cyclic AMP (dBc)-treated NG cells (NG-dBc-CM) but not by CM from dBc-treated NCB cells, (NCB-dBc-CM).

Ni-coupled receptors in cultured neural hybrid cells: cell specificity for dibutyryl cyclic AMP-induced down-regulation but not morphological differentiation.

Opiate, muscarinic, and alpha 2-adrenergic receptors and the Ni-coupled response of adenylate cyclase (AC) inhibition were examined in neuroblastoma X glioma NG108-15 (108 CC15) and neuroblastoma X Chinese hamster brain NCB-20 clonal hybrid cells, induced to differentiate with 1.0 mM dibutyryl cAMP (dBcAMP). Scatchard analysis of binding of the opiate agonist 3H-(D-Ala2,D-Leu5)enkephalin (DADLE) and the antagonist [3H] diprenorphine to dBcAMP-treated NCB-20 cell membranes indicated an 80% reduction in opiate receptor density relative to untreated cells (Bmax = 47 +/- 11 fmol/mg of protein versus 220 +/- 48 fmol/mg of protein), with no change in ligand affinities.

Pharmacological profile of adenosine A2 receptor in PC12 cells.

The PC12 cell line, a clone isolated from a pheochromocytoma tumor of rat adrenal medulla, was shown to exclusively contain stimulatory adenosine (A2) receptors linked to adenylate cyclase (AC). AC was stimulated 6-7 fold by several agonists with a rank order of potency of 5'-N-Ethyl carboxamidoadenosine (NECA) greater than 2-Chloroadenosine (2-CADO) greater than (R)-N-Phenylisopropyladenosine (R-(-)-PIA) greater than N6-Cyclopentyladenosine (CPA) greater than N6-Cyclohexyladenosine (CHA) greater than S-(+)-PIA. AC activity was antagonized by a variety of adenosine receptor antagonists with a potency order of 1,3,-Dipropyl-8-(2-amino-4-chlorophenyl)xanthine (PACPX) greater than 1,3,-Diethyl-8-phenylxanthine (DPX) greater than 8-Phenyltheophylline greater than 3-Isobutyl-1-methylxanthine (IBMX) greater than 8-(p-sulfophenyl)theophylline (PST) greater than 7-(beta-chloroethyl)theophylline greater than theophylline = enprofylline = caffeine.

Antagonism of cisplatin-induced emesis by metoclopramide and dazopride through enhancement of gastric motility.

The antiemetic activity, gastric motor activity, and dopamine receptor effects of metoclopramide, dazopride, and sulpiride were assessed to establish if enhancement of gastric motility or antagonism of central dopamine receptors is the predominant action for drug-induced suppression of cisplatin-induced emesis. Emesis produced in dogs by cisplatin is antagonized by metoclopramide and dazopride. The antiemetic actions of metoclopramide and dazopride are associated with their ability to enhance gastric motor activity.

In vivo phosphorylation of postsynaptic density proteins.

In vivo protein phosphorylation was examined in postsynaptic density-enriched fractions isolated from rat brain. In vivo phosphorylation was carried out by injecting rats intraventricularly with [32P]orthophosphate followed by isolation of postsynaptic densities from pooled cerebral cortices. In vivo 32P-labeled postsynaptic densities were then fractionated by sodium dodecylsulfate-polyacrylamide slab gel electrophoresis and stained with Coomassie Blue.

Neurochemical properties of AHR-9377: a novel inhibitor of norepinephrine reuptake.

A novel potential antidepressant, AHR-9377, was evaluated for its inhibition of norepinephrine (NE), serotonin (5-HT) and dopamine (DA) reuptake in hypothalmic, cortical, and striatal rat synaptosomal preparations. AHR-9377 was found to be a potent, selective, noncompetitive inhibitor of NE reuptake. In addition, repeated injections of AHR-9377 caused a decrease in the density of beta adrenergic receptors in rat cerebral cortex.

Down regulation of dihydroalprenolol and imipramine binding sites in brain of rats repeatedly treated with imipramine.

In rats receiving repeated injections of imipramine, there is a reduction in the number of high affinity binding sites for [3H]imipramine and [3H]dihydroalprenolol present in crude synaptic membrane preparations from various brain structures. The location of the sites that become subsensitive to the two ligands did not coincide; the binding sites to [3H]imipramine became subsensitive in the hippocampus but not in cortex or cerebellum. In contrast the binding sites to [3H]dihydroalprenolol became subsensitive in cortex and cerebellum but not in hippocampus.

Protein phosphorylation in rat caudate homogenate: stimulatory effects of dopamine and enhancement of dopamine response following 6-hydroxydopamine treatment.

Dopamine (3-hydroxytyramine) stimulates the incorporation of 32P into proteins endogenous to a homogenate of rat caudate nucleus when 10 microM [gamma-32P]-ATP is used as a substrate following preincubation with 400 microM ATP. The increase in 32P incorporation has pharmacological characteristics similar to caudate tissue. Chronic depletion of striatal dopamine in vivo by stereotaxic injection of 6-hydroxydopamine in the nigrostriatal pathway results in a significant enhancement of the dopamine stimulation of 32 p incorporation in vitro.

Soluble and membrane-bound protein kinases in newborn and mature rat brain.

We studied the developmental changes of soluble and membrane-bound protein kinases (EC 2.7.1.