Specific beta-adrenergic receptors present in membrane preparations of frog erythrocytes were identified by binding of (-)-[3H]dihydroalprenolol, a potent competitive beta-adrenergic antagonist. The (-)-[3H]dihydroalprenolol binding sites could be solubilized by treatment of a purified erythrocyte membrane fraction with the plant glycoside digitonin but not by treatment with a wide variety of o...

Administration of enantiomerically pure β-adrenergic agonists and antagonists increases their activity and reduces side effects. We report here a small-molecule artificial receptor (SMAR) that, by mimicking the β-adrenergic receptor, is able to enantioselectively extract commercial β-adrenergic interacting drugs. The selectivity is justified according to DFT calculations and X-ray diffraction e...

Naringin is a flavonoid glycoside found in citrus fruits and grapes with wide range of therapeutic actions. We aimed to study the inotropic effect naringin on rat-isolated atria, dissecting intracellular mechanisms involved this response. Concentration-response curves (0.003-6 mM) were obtained before after pre-incubation selective antagonists. Our results showed that presented biphasic respons...

The possibility that monoamines might act as signalling molecules during the early development of the nervous system has been examined in embryos of the amphibian Xenopus laevis. The distributions of 5-hydroxytryptamine, dopamine, noradrenaline and their precursor, dopa, were determined from the fertilized egg up to the late neurula stages using High Performance Liquid Chromatography, formaldeh...

PURPOSE For the treatment of glaucoma, alpha-2 adrenergic receptor (alpha 2-AR) agonists are thought to lower intraocular pressure primarily by decreasing aqueous humor production. Effects on the outflow pathways, however, also may occur. To begin to examine this possibility, the authors characterized the alpha 2-AR subtypes present in cultures of human trabecular meshwork (HTM) cells using bot...

To investigate the possible role of arginine vasopressin in maintaining high blood pressure of spontaneously hypertensive rats (SHR), the effect of two arginine vasopressin pressor antagonists on mean arterial pressure and the pressor responsiveness to exogenous arginine vasopressin were studied in conscious, freely moving SHR and in Wistar-Kyoto rats (WKY). Intravenous injections of either d(C...

The brain stem provides most of the noradrenaline (NA) present in the spinal cord, which functions to both increase spinal motoneuron excitability and inhibit sensory afferent transmission to motoneurons (excitatory postsynaptic potentials; EPSPs). NA increases motoneuron excitability by facilitating calcium-mediated persistent inward currents (Ca PICs) that are crucial for sustained motoneuron...

We have used two different cultured cell lines—S49 lymphoma cells and BC3H-1 muscle cells— to examine the regulation of /3-adrenergic receptors by receptor antagonists. Rather than an increase ("up-regulation") of receptor number that such antagonists often produce, we found that certain /3-blockers elicit a decrease ("down-regulation") of beta-adrenergic receptors. Alprenolol and propranolol, ...