Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Butaclamol”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28Linked to original sources
PubMedDate not supplied

Blockade of dopamine receptors in the renal vasculature by isomers of flupenthixol and sulpiride.

We studied the renal vascular effects of flupenthixol and sulpiride isomers in the isolated perfused rat kidney in the presence of phenoxybenzamine (10(-5) M) and sotalol (10(-5) M). The vascular bed was contracted with prostaglandin F2 alpha (10(-7) -3 X 10(-6) M) and dose-dependently relaxed with dopamine. Cis-flupenthixol (10(-9)-10(-7) M) antagonized competitively the response to dopamine (apparent pA2 = 8.34 +/- 0.09; mean +/- SD) without affecting papaverine-induced relaxation. Trans-flupenthixol was without effect at 10(-7) M. The dopamine receptor antagonist activities of the sulpiride isomers are low and d-sulpiride is twice as active as 1-sulpiride. Thus, the renal vascular dopamine receptor can be further characterized by the relative antagonist activities of cis-flupenthixol and sulpiride and by a rather low stereospecificity in favor of d-sulpiride.

Animals↗
PubMed1983

Effects of vasoactive intestinal peptide and other peptides on cyclic AMP accumulation in intact pieces and isolated horizontal cells of the teleost retina.

The effects of vasoactive intestinal peptide (VIP) and several other peptides have been examined on cyclic AMP accumulation in intact pieces and isolated horizontal cells of the teleost (carp) retina. VIP was the most effective peptide examined, inducing a dose-related response, and an approximately fivefold increase in cyclic AMP production when used at a concentration of 10 microM. Porcine histidine isoleucine-containing peptide and secretin, peptides structurally related to VIP, also stimulated cyclic AMP accumulation, but at concentrations of 10 microM induced responses which were only approximately 40% and 10%, respectively, of the response observed with 10 microM VIP. In contrast, several other peptides, including glucagon, neurotensin, somatostatin, luteinizing hormone-releasing hormone, alpha-melanocyte-stimulating hormone, cholecystokinin octapeptide26-33, gastrin-releasing peptide, thyrotropin-releasing hormone, and VIP10-28 were totally inactive. The response to 10 microM VIP was not antagonized by several dopamine antagonists, indicating the presence of a population of specific VIP receptors coupled to adenylate cyclase, distinct from the population of dopamine receptors coupled to adenylate cyclase also known to be present in this tissue. Finally, experiments involving the use of fractions of isolated horizontal cells indicate that these neurons possess a population of VIP receptors coupled to cyclic AMP production which would appear to share a common pool of adenylate cyclase with a population of similarly coupled dopamine receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1985

D2 dopamine receptors in calf globus pallidus: agonist high- and low-affinity sites not regulated by guanine nucleotide.

By use of the radioligand [3H]spiroperidol, D2 3,4-dihydroxyphenylethylamine (dopamine) receptor binding characteristics were studied in calf globus pallidus and compared with those of neostriatum. Antagonist competition curves were monophasic and revealed similar affinities for neostriatum and globus pallidus, suggesting a uniform receptor population with one affinity state for antagonists. In both regions, competition curves with the agonist dopamine were biphasic, distinguishing a high- and low-agonist-affinity state. In neostriatum and globus pallidus, respectively, 45% and 19% of [3H]spiroperidol binding was displaced with high affinity and the remainder with low affinity. In neostriatum, the addition of 0.4 mM GTP resulted in a partial conversion from high- to low-affinity state with a remaining high-affinity component of 15%. In globus pallidus, dopamine binding was not altered by GTP. The capability of GTP to modulate agonist binding to D2 receptors appears to be dependent on their neuroanatomical localization.

Animals↗
PubMed1985

Drug potencies on partially purified brain D2 dopamine receptors.

To examine the sensitivities of partially purified dopamine receptors to various dopaminergic agonists and antagonists, canine brain striatum dopamine receptors were enriched by isoelectric focusing. The digitonin-solubilized receptors were prelabelled with [3H]spiperone and focused for two time periods. After 5 h (incomplete focusing), radioactive peaks were detected at pH 6 and 9-11. Only the pH 6 peak revealed drug sensitivities expected of D2 receptors. Receptor recovery of the pH 6 peak was 79% with purification being sevenfold. After focusing overnight to equilibrium, the pH 6 peak further separated into peaks at pH 4.6 and 6.8. The receptor was identified only in the pH 4.6 fraction. The recovery of receptors in the pH 4.6 peak was low (10%), indicating little enrichment of the receptor. The rank order of binding of neuroleptics and dopamine agonists to the purified material was similar to that of the original preparation of soluble receptors. Dopamine did not bind to the purified pH 4.6 fraction unless the phosphate buffer (used during focusing) was replaced with Tris buffer. The absence of receptors in the pH 6.8 and pH 10 fractions, although both contained prelabeled [3H]spiperone, indicates the importance of testing agonists and antagonists on each fraction at each step in purification.

Animals↗
PubMed2005

Secretion of brain-derived neurotrophic factor from PC12 cells in response to oxidative stress requires autocrine dopamine signaling.

Expression of brain-derived neurotrophic factor (BDNF) is sensitive to changes in oxygen availability, suggesting that BDNF may be involved in adaptive responses to oxidative stress. However, it is unknown whether or not oxidative stress actually increases availability of BDNF by stimulating BDNF secretion. To approach this issue we examined BDNF release from PC12 cells, a well-established model of neurosecretion, in response to hypoxic stimuli. BDNF secretion from neuronally differentiated PC12 cells was strongly stimulated by exposure to intermittent hypoxia (IH). This response was inhibited by N-acetyl-l-cysteine, a potent scavenger of reactive oxygen species (ROS) and mimicked by exogenous ROS. IH-induced BDNF release requires activation of tetrodotoxin sensitive Na+ channels and Ca2+ influx through N- and L-type channels, as well as mobilization of internal Ca2+ stores. These results demonstrate that oxidative stress can stimulate BDNF release and that underlying mechanisms are similar to those previously described for activity-dependent BDNF secretion from neurons. Surprisingly, we also found that IH-induced secretion of BDNF was blocked by dopamine D2 receptor antagonists or by inhibition of dopamine synthesis with alpha-methyl-p-tyrosine. These data indicate that oxidative stress can stimulate BDNF release through an autocrine or paracrine loop that requires dopamine receptor activation.

Animals↗
PubMed1985

Brain dopamine and serotonin receptor sites revealed by digital subtraction autoradiography.

Autoradiography combined with image analysis permitted quantitative visualization of dopamine (D2) and serotonin (S2) binding sites in rat brain. Forebrain sections were incubated with tritiated spiroperidol alone or with tritiated spiroperidol plus unlabeled compounds that saturated the D2 or S2 sites. By subtracting the digitized image of an autoradiograph derived from the latter sections from that of the former, the D2 or S2 sites were specifically revealed. The resulting quantitative images demonstrate the differing anatomical distributions of these sites. The D2 site is largely restricted to the striatal complex (caudate-putamen, nucleus accumbens septi, and olfactory tubercle), whereas the S2 site is enriched in layer 5 of motor cortex, the perirhinal and cingulate cortices, and the claustrum.

Animals↗
PubMed1981

Sodium-dependent interaction of benzamides with dopamine receptors in rat and dog anterior pituitary glands.

Sulpiride and other benzamides' displacement of [3H]-spiroperidol binding to rat and dog anterior pituitary dopaminergic receptors was found to be selectively sodium dependent, while typical neuroleptic activity was not influenced by NaCl. These results indicate the existence in the anterior pituitary of a subpopulation of dopaminergic receptors with which benzamides interact.

Animals↗
PubMed1984

Localization of dopamine receptors in the rabbit renal artery: a histoautoradiographic study.

The localization of dopamine receptors within rabbit renal artery was studied using 3H-spiroperidol as a label for dopamine receptors and a histoautoradiographic technique. Preliminary radioreceptor binding studies showed that 3H-spiroperidol was bound to sections of renal artery in a manner consistent with the existence of dopamine receptors. In fact the binding was found to be saturable, stereospecific and of high affinity, with a Bmax approximately of 158.3 fmol/mg protein and a Kd of 13.5 nmol/l. The microscopic examination of sections processed for the histoautoradiographic demonstration of 3'-spiroperidol binding sites showed that the distribution of dopamine receptors in the renal artery was widespread. The highest concentration of dopamine receptors was found primarily in the smooth muscle cells of the media and then, in the following order, in endothelial cells of the intima and in fibrous and connective cells of the adventitia. The direct demonstration of dopamine receptors in the media of rabbit renal artery strongly supports the hypothesis that these receptors may be involved in the relaxation of the artery caused by infusion or application of dopamine.

Animals↗
PubMed1994

The D2 dopamine receptor mediates inhibition of growth in GH4ZR7 cells: involvement of protein kinase-C epsilon.

The D2 dopamine agonist, bromocriptine, has been used as treatment for human PRL-secreting pituitary adenomas. The result of bromocriptine treatment is often a substantial reduction of tumor mass, suggesting that the dopamine agonist is acting as an antiproliferative agent. This action can be observed with a clonal pituitary tumor cell line. The agonist activation of the D2 dopamine receptor inhibits the growth of GH4ZR7 cells, a GH4C1 cell line stably transfected with the cDNA encoding the short form of the D2 dopamine receptor. This effect of dopamine was not sensitive to overnight treatment with 100 ng/ml pertussis toxin. Treatment of GH4ZR7 cells with the phorbol ester 4 beta-phorbol 12,13-didecanoate resulted in the loss of dopaminergic inhibition of growth, whereas treatment with 4 alpha-phorbol 12,13-didecanoate had no effect. Inhibitors of protein kinase-C (PKC), such as staurosporine and H7, also blocked the effect of dopamine. Down-regulation of cellular PKC by phorbol ester treatment resulted in a complete loss of dopaminergic inhibition of growth. Long term treatment of GH4ZR7 cells with TRH results in a specific down-regulation of the epsilon form of PKC and abolished the ability of dopamine to inhibit growth. These results suggest that PKC epsilon is involved in mediating the antiproliferative effects of dopamine. This mediation of growth appears to be through a novel signaling pathway for the D2 dopamine receptor.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1987

Dopamine D2 receptors in the rat brain: autoradiographic visualization using a high-affinity selective agonist ligand.

The non-catechol, selective dopamine D2-agonist compound 3H-205-502 was used to localize dopamine D2 receptors by autoradiography after in vitro labeling of brain sections. The characteristics of the binding of this ligand to tissue sections were those expected from the labeling of dopamine D2 receptors. The binding of 3H-205-502 was inhibited selectively and stereospecifically by dopamine D2 agents but not by dopamine D1 compounds. The autoradiographic localization of 3H-205-502 binding sites showed high densities of dopamine D2 receptors in areas such as the glomerular layer of the olfactory bulb, the nucleus accumbens, caudate-putamen, olfactory tubercle, the lateral septum, and the islands of Calleja. Besides these dopamine-innervated areas the substantia nigra and the ventral tegmental area also showed important receptor densities. Other areas where dopamine D2 receptor binding was found were the stratum lacunosum-moleculare of the hippocampus, bands of labeling in the molecular layer of the 9th and 10th lobules of the cerebellum, and several components of the visual system. This distribution presents similarities and differences with previously reported distributions of dopamine D2 receptors visualized autoradiographically using 3H-labeled agonists and antagonists. In view of the high affinity, guanine nucleotide insensitivity, and dopamine D2 selectivity of this agonist ligand, it is suggested that dopamine D2 receptors exist in different states in different areas. 3H-205-502 appears to be a new and useful tool for the study of dopamine D2 receptors.

Aminoquinolines↗
PubMed1987

Calmodulin and troponin C as targets for drug action.

In this study, ligands from various chemical classes were investigated with respect to their relative affinities to calmodulin (CaM) and troponin C (TnC), using the fluorescent dye 3,3'-dipropylthiocarbocyanine iodide (diS-C3-5'). In parallel, functional tests were carried out determining the effects of the ligands on the CaM activated cyclic nucleotide phosphodiesterase (PDE) activity and the TnC mediated Ca-sensitivity of skinned myocardial fibres and cardiac myofibrils. The following results were obtained: 1) As a rule, most of the ligands tested had higher affinities to CaM than to TnC. 2) Even within one and the same pharmacological class (e.g. phenothiazines) the relative affinities for CaM and TnC varied considerably, trifluoperazine (TFP) or levomepromazine (LMP) showing low or no CaM specificity, methophenazine (MP) on the other hand being highly selective for CaM by a factor of more than 200. 3) In all cases tested, the functional tests were in good quantitative agreement with the binding data, showing inhibition of CaM stimulated PDE activity and Ca-sensitizing effects in concentrations corresponding well with the respective drug affinities to CaM and TnC, respectively. 4) It is concluded that a) interaction of ligands with TnC can lead to Ca-sensitization of the cardiac contractile system and a positive inotropic effect without a concomitant elevation of the intracellular level of activator Ca. This may result in a novel cardiotonic principle avoiding the common side effects of 'classical' positive inotropic agents due to Ca-overload. b) drug selectivity for TnC or CaM appears chemically achievable.

Animals↗