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showing 10 items of 5147 documents
0149: Agonistic anti β3-adrenoceptor antibodies do not affect the β1-adrenoceptor-mediated inotropy and the β3 adrenoceptor-mediated vasorelaxation i…
2014
Cardiac activity of autoantibodies (AABs) directed against β1-adrenoceptor (β1-AR) has been proposed to play an important role in the pathogenesis of dilated cardiomyopathy. Our previous work has shown that the immunization of rats with the second extracellular loop (ECII) of β1-AR induced endothelial dysfunction in aorta and mesenteric arteries. However, until now, no study has explored the cardiovascular effects of β3-AABs alone or combined with β1-AABs.AimTo evaluate whether β3-AABs possess β3-AR agonistic effect and whether active immunization producing β3-AABs and/or β1-AABs has deleterious effects on cardiac and vascular reactivity in Lewis rats.MethodsLewis rats were immunized for 3 …
Histaprodifens: synthesis, pharmacological in vitro evaluation, and molecular modeling of a new class of highly active and selective histamine H(1)-r…
2000
A new class of histamine analogues characterized by a 3, 3-diphenylpropyl substituent at the 2-position of the imidazole nucleus has been prepared outgoing from 4,4-diphenylbutyronitrile (4b) via cyclization of the corresponding methyl imidate 5b with 2-oxo-4-phthalimido-1-butyl acetate or 2-oxo-1,4-butandiol in liquid ammonia, followed by standard reactions. The title compounds displayed partial agonism on contractile H(1) receptors of the guinea-pig ileum and endothelium-denuded aorta, respectively, except 10 (histaprodifen; 2-[2-(3, 3-diphenylpropyl)-1H-imidazol-4-yl]ethanamine) which was a full agonist in the ileum assay. While 10 was equipotent with histamine (1), methylhistaprodifen (…
Pretreatment with gonadotropin-releasing hormone (GnRH) antagonists to prevent the flare-up effect of long-acting GnRH agonists: results of a pilot s…
2007
This study evaluated in vivo whether the flare-up effect of GnRH agonists can be suppressed through pretreatment with a GnRH antagonist. The classic flare-up effect caused by 3.8 mg goserelin acetate could not be suppressed through pretreatment using a single dosage of 3.24 mg cetrorelix acetate.
Involvement of tachykinin NK2 receptors in the modulation of spontaneous motility in rat proximal colon.
2000
The role of endogenous tachykinins and the mechanisms whereby they act on NK2 receptors, modulating spontaneous motility, were investigated in rat isolated proximal colon. The mechanical activity was detected as changes in intraluminal pressure. The NK2 receptor antagonist, MEN 10627, produced a concentration-dependent reduction of the contraction amplitude. [beta-Ala8]-neurokinin A(4-10), an NK2 receptor agonist, and [Sar9, Met(O2)11]-Substance P ([Sar9, Met(O2)11]-SP), an NK1 receptor agonist, induced a concentration-dependent contractile response, characterized by an increase in basal tone with superimposed phasic contractions. MEN 10627 antagonized the response to [beta-Ala8]-neurokinin…
Modulation by 5-HT3 and 5-HT4 receptors of the release of 5-hydroxytryptamine from the guinea-pig small intestine.
1993
The effects of agonists and antagonists of 5-hydroxytryptamine (5-HT) receptors on the release of endogenous 5-HT from enterochromaffin cells were studied in the vascularly perfused isolated guinea-pig small intestine. The experiments were done in the presence of tetrodotoxin in order to exclude a neuronally mediated influence on 5-HT release. The 5-HT3 receptor agonist 2-methyl-5-HT increased 5-HT release, and this effect was antagonized by 1 nmol/l tropisetron. Nanomolar concentrations of tropisetron, MDL 72,222 and granisetron decreased 5-HT release. Ondansetron (0.1 and 1 mumol/l) did not modify 5-HT release. 5-Methoxytryptamine, BIMU8 and cisapride concentration-dependently inhibited 5…
Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF r…
2006
No specific treatment is available for ovarian hyperstimulation syndrome (OHSS), the most important complication in infertile women treated with gonadotropins. OHSS is caused by increased vascular permeability (VP) through ovarian hypersecretion of vascular endothelial growth factor (VEGF)activating VEGF receptor 2 (VEGFR-2). We previously demonstrated in an OHSS rodent model that increased VP was prevented by inactivating VEGFR-2 with a receptor antagonist(SU5416).However,duetoitstoxicity(thromboembolism) and disruption of VEGFR-2-dependent angiogenic processes critical for pregnancy, this kind of compound cannot be used clinically to prevent OHSS. Dopamine receptor 2 (Dp-r2) agonists, use…
The role of gonadotropin-releasing hormone in murine preimplantation embryonic development.
1999
Previous studies have established the presence of an extrahypothalamic GnRH in a variety of tissues. GnRH receptor is known to be present in the placenta, which produces and secretes the decapeptide from the very early stages of placentation. We hypothesized that GnRH may play a role in the preimplantation development of embryos. To examine this hypothesis, we assessed GnRH and GnRH receptor messenger RNA (mRNA; RT-PCR) and protein expression (Immunohistochemistry) in preimplantation murine embryos at various developmental stages. Furthermore, preimplantation murine embryos were cultured with GnRH agonist and antagonist in vitro to assess the influence of GnRH analogs on embryo development.…
Endothelin receptors mediating contraction in goat cerebral arteries
1993
1. The aim of the present study was to identify the subtype of receptor mediating contraction to endothelin-1 and sarafotoxin S6b in goat isolated middle cerebral arteries. 2. Endothelin-1, endothelin-2 and endothelin-3 contracted cerebral arteries in a concentration-dependent manner. Although the three peptides were full agonists, the order of potency was endothelin-1 = endothelin-2 > endothelin-3, with a relative potency of endothelin-1 and endothelin-2 versus endothelin-3 of approximately 280. Sarafotoxin S6b induced concentration-dependent contractions with lower potency than endothelin-1/endothelin-2, higher potency than endothelin-3 and a higher maximum response than the three endothe…
Subtype-Specific Desensitization of Human Endothelin ETA and ETB Receptors Reflects Differential Receptor Phosphorylation
1997
Endothelins regulate blood pressure in mammals through G protein-coupled receptors. Two receptor subtypes, ETA and ETB, exist which differ by their agonist profiles. Here we show subtype-specific differences in the inactivation of these endothelin receptors. Using a modified inositol phosphate accumulation assay, we found that stimulation of ETA by endothelin-1 results in sustained activation of the subtype, retaining >30% of its initial activity even 20 min after agonist administration, whereas the ETB rapidly deactivated after agonist stimulation, losing >80% of its initial activity within 5 min after endothelin application. The discrepancy in receptor inactivation is reflected by subtype…
Endothelin Antagonism: Effects of FP Receptor Agonists Prostaglandin F2αand Fluprostenol on Trabecular Meshwork Contractility
2006
Purpose This study analyzes additional mechanisms behind the ocular hypotensive effect of prostaglandin F (PGF) receptor (FP receptor) agonists PGF2alpha and fluprostenol (fluprostenol-isopropyl ester [travoprost]), which reduce intraocular pressure (IOP) in patients with glaucoma probably by enhancing uveoscleral flow. The trabecular meshwork (TM) is actively involved in IOP regulation through contractile mechanisms. Contractility of TM is induced by endothelin (ET)-1, a possible pathogenic factor in glaucoma. The involvement of FP receptor agonists in the ET-1 effects on TM function was studied. Methods The effects of FP receptor agonists on contractility of bovine TM (BTM) were investiga…