Search results for "Rauwolscine"
showing 6 items of 6 documents
Adrenoceptors in GtoPdb v.2021.3
2021
The nomenclature of the Adrenoceptors has been agreed by the NC-IUPHAR Subcommittee on Adrenoceptors [60, 186]. Adrenoceptors, α1 The three α1-adrenoceptor subtypes α1A, α1B and α1D are activated by the endogenous agonists (-)-adrenaline and (-)-noradrenaline. -(-)phenylephrine, methoxamine and cirazoline are agonists and prazosin and doxazosin antagonists considered selective for α1- relative to α2-adrenoceptors. [3H]prazosin and [125I]HEAT (BE2254) are relatively selective radioligands. S(+)-niguldipine also has high affinity for L-type Ca2+ channels. Fluorescent derivatives of prazosin (Bodipy FLprazosin- QAPB) are used to examine cellular localisation of α1-adrenoceptors. α1-Adrenocepto…
Adrenoceptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database
2019
The nomenclature of the Adrenoceptors has been agreed by the NC-IUPHAR Subcommittee on Adrenoceptors [58], see also [180]. Adrenoceptors, α1α1-Adrenoceptors are activated by the endogenous agonists (-)-adrenaline and (-)-noradrenaline. phenylephrine, methoxamine and cirazoline are agonists and prazosin and cirazoline antagonists considered selective for α1- relative to α2-adrenoceptors. [3H]prazosin and [125I]HEAT (BE2254) are relatively selective radioligands. S(+)-niguldipine also has high affinity for L-type Ca2+ channels. Fluorescent derivatives of prazosin (Bodipy PLprazosin- QAPB) are used to examine cellular localisation of α1-adrenoceptors. Selective α1-adrenoceptor agonists are use…
Desensitization of inhibitory prejunctional alpha 2-adrenoceptors and putative imidazoline receptors on rabbit heart sympathetic nerves.
1993
To find out whether sympathetic nerves of the rabbit heart possess pharmacologically relevant prejunctional imidazoline receptors different from α-autoreceptors, the inhibition by oxymetazoline, aganodine and BDF 6143 (4-chloro-2-[2-imidazoline-2-ylamino]-isoindoline hydrochloride) of endogenous noradrenaline overflow evoked by stimulation of extrinsic postganglionic sympathetic nerves (0.66 Hz, 80 pulses) was investigated. In addition we wanted to find out whether either type of these prejunctional receptors undergoes desensitization upon pre-exposure to respective agonists. The α2-adrenoceptor agonist oxymetazoline inhibited the evoked noradrenaline overflow (2.9 nmol/l, IC50; about 90010…
Characterization of sensory neurotransmission and its inhibition via alpha 2B-adrenoceptors and via non-alpha 2-receptors in rabbit iris.
1993
To find out whether, and which type of, adrenoceptors mediate prejunctional inhibition of sensory neurotransmitter release from trigeminal fibres, the modulation of twitch response to electrical field stimulation on rabbit isolated iris was investigated. Evoked iris sphincter contractions consisted of a minor fast cholinergic and a large slow component. The latter was unaffected by atropine and guanethidine, hence nonadrenergic noncholinergic in nature (NANC), but nearly completely abolished by capsaicin pretreatment and by the neurokinin receptor antagonist spantide. The response was probably not mediated by NK2 receptors as SR 48,968, an NK2 selective nonpeptide antagonist, failed to redu…
Adrenoceptor- and cholinoceptor-mediated mechanisms in the regulation of 5-hydroxytryptamine release from isolated tracheae of newborn rabbits
1996
Abstract 1. Isolated tracheae of newborn rabbits were incubated in vitro and the outflow of 5-hydroxytryptamine (5-HT) was determined by h.p.l.c. with electrochemical detection. Evidence has previously been provided that this 5-HT outflow derives from neuroendocrine epithelial (NEE) cells of the airway mucosa. 2. Phenylephrine (1, 10 and 30 microM) enhanced the outflow of 5-HT by 80, 290 and 205%, respectively. 5-HT outflow evoked by 10 microM phenylephrine was not affected by the presence of the neurotoxin tetrodotoxin (1 microM). 3. Rauwolscine, ARC 239 (an alpha(2B)-adrenoceptor preferring antagonist), yohimbine and prazosin antagonized the effect of 10 microM phenylephrine in a concentr…
Identification of α2-adrenoceptors and non-adrenergic idazoxan binding sites in rabbit colon epithelial cells
1990
alpha 2-Adrenoceptors are possibly involved in the regulation of the hydroelectrolytic flux across the digestive mucosa. As no data are available concerning the existence of these receptors in colon epithelial cells, we aimed to investigate the existence of alpha 2-adrenoceptors in this tissue using tritiated antagonists. [3H]Yohimbine and [3H]rauwolscine were not usable to label colonic alpha 2-adrenoceptors because of their very high level of non-specific binding. In contrast, the methoxy derivative of idazoxan, [3H]RX821002, appeared a convenient radioligand for the purpose. [3H]RX821002 bound with high affinity (KD = 6.2 +/- 0.8 nM) to a single population of non-interacting sites (Bmax …