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Pharmacological Characterization of 5-Hydroxytryptamine Receptors in the Gastrointestinal Tract
Published in T.S. Gaginella, J.J. Galligan, SEROTONIN and GASTROINTESTINAL FUNCTION, 2020
Jeremy D. Gale, Keith T. Bunce
As previously mentioned, the 5-HT2B receptor is the current nomenclature for the receptor mediating the contraction elicited by 5-HT in the rat gastric fundus.83,84 In this preparation, 5-HT is an agonist with high potency (EC50 = 87 nM).61 Other agonists at this receptor include MK-212 (full agonist, 100-fold weaker than 5-HT) and quipazine (partial agonist, 100-fold weaker than 5-HT). However, both quipazine and MK-212 have agonist and/or antagonist activity at a wide range of other 5-HT receptors. The response to 5-HT can be antagonized competitively by yohimbine (pA2 = 8.5) and rauwolscine (pA2 = 8.5),61 both these drugs are classically regarded as being relatively selective for α2-adrenoceptors. Furthermore, the effects of 5-HT can be blocked noncompetitively by LY 53857, methysergide, and metergoline.61 Recently, a competitive antagonist at this receptor has been described, SB 200646 (pA2 = 7.5).85 This compound does not discriminate between 5-HT2B and 5-HT2C receptors, but has 100-fold selectivity over other receptor subtypes.
Central Nervous System Circuitry Involved in Blood Pressure Regulation
Published in Fuad Lechin, Bertha van der Dijs, Neurochemistry and Clinical Disorders: Circuitry of Some Psychiatric and Psychosomatic Syndromes, 2020
Fuad Lechin, Bertha van der Dijs, Jose Amat, Simon Villa, Alex E. Lechin
Some data indicate that the specific a,-antagonist prazosin acts centrally to reduce sympathetic nervous discharge (SND), when intraventricularly injected. Such observations suggest that NE neurons facilitate central sympathetic outflow and that clonidine acts by decreasing activity in noradrenergic pathways (disfacilitation). These findings are consistent with others showing that a2-antagonists increase central NE turnover as well as the firing rate of some NE neurons. Further, a broad range of i.v. doses of piperoxane and rauwolscine (two a2 blocking agents) increases sympathetic nervous discharge. These results are compatible with the hypothesis that at least some central NE neurons facilitate sympathetic nervous discharge.3,6-28,33-41,46-50,53-60,65-77,82-107,112-116,121,122,127-130,148-199,206-228,232-237,244,251,254,257,260,262,265-271,275-284,288-297,303,306-311,316-324,328-335,342,343,354-356,363-366,373-380,400-420
Adrenoceptor Antagonists
Published in Kenneth J. Broadley, Autonomic Pharmacology, 2017
This is a naturally occurring indolealkylamine alkaloid obtained from the bark of the Pausinystalia yohimbe tree and from Rauwolfia root (also the source of reserpine to which it is structurally related). Yohimbine, corynanthine and rauwolscine have the same structural formula but are diastereoisomers (Table 5.2). Of these, corynanthine is α1-selective while rauwolscine and yohimbine are selective α2-adrenoceptor antagonists. They are competitive antagonists with pA2 values at α1-adrenoceptors of 6.5–7.4, 5–7 and 5–7 for corynanthine, rauwolscine and yohimbine, respectively, while at α2-adrenoceptors their respective pA2 values are 4–6, 7.5–8.5 and 7–9, respectively (Wilson et al. 1991). The rigid structure prevents conformational changes to the molecule and corynanthine has been used as a model for the confirmational requirements for interaction with the α1-adrenoceptor (DeMarinis et al. 1987).
α1-Adrenergic receptors increase glucose oxidation under normal and ischemic conditions in adult mouse cardiomyocytes
Published in Journal of Receptors and Signal Transduction, 2021
Robert S. Papay, Dianne M. Perez
To assess the signal transduction pathway mediated by α1-ARs, the following list of reagents were used: α1-AR agonist 100 μM phenylephrine HCl (Sigma-Aldrich, St. Louis, MO, P-6126) in the presence of 1 μM propranolol and 0.1 μ M rauwolscine to block β- and α2-ARs respectively, nonselective α1-AR antagonist prazosin (1 μ M; Sigma-Aldrich, P-7791), Etomoxir (250uM, Tocris 4539); dorsomorphin dihydrochloride (50uM, Santa Cruz sc-361173); Rottlerin (5uM, Tocris 1610); 2 Deoxy-D-Glucose (50 mM, Sigma D3179).
Pharmacological characterization of the α2A-adrenergic receptor inhibiting rat hippocampal CA3 epileptiform activity: comparison of ligand efficacy and potency
Published in Journal of Receptors and Signal Transduction, 2022
Joseph P. Biggane, Ke Xu, Brianna L. Goldenstein, Kylie L. Davis, Elizabeth J. Luger, Bethany A. Davis, Chris W.D. Jurgens, Dianne M. Perez, James E. Porter, Van A. Doze
ARC-239, BRL-44408, clonidine hydrochloride, dexmedetomidine hydrochloride, efaroxan hydrochloride, guanabenz acetate, guanfacine hydrochloride, idazoxan hydrochloride, JP-1302, prazosin hydrochloride, rauwolscine hydrochloride, RS-79948, RX-821002, terazosin, UK-14304, WB-4101, and yohimbine hydrochloride were acquired from Tocris (Ellisville, MO). Atipamezole was from Orion Corporation (Espoo, Finland) and isoflurane was from Abbott Diagnostics (Chicago, IL). All other chemicals were obtained from Sigma-Aldrich (St. Louis, MO).