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Fulltext Claustrophobia in MRI: is there a role for dexmedetomidine? An observational case series study involving 11 patients

Rai, V., Norhasayani, T., Chan, L.

JUMMEC, 2013;16(1):1-4.
MyJurnal

MRI can be a distressing and traumatic experience in many patients, especially in those with underlying anxiety and/or claustrophobia. We conducted a study to determine if dexmedetomidine as a sedative agent can alleviate these symptoms. Dexmedetomidine is a potent and highly selective α-2 adrenergic receptor agonist which has sedative and analgesic properties. Eleven adult patients (n=11) with a histroy of anxiety and/or claustrophobia undergoing MRI who expressed their desire for sedation were recruited. Dexmedetomidine was infused at 0.5 to 1.0 μg/kg over 10 minutes prior to scanning. Eight patients (n=8) were able to complete the MRI scan comfortably. The findings suggest that dexmedetomidine provides adequate sedation that can allow patients with anxiety and/or claustrophobia to undergo MRI scanning succesfully in a large poproption of the population with anxiety. This result however is still preliminary and will need to be validated in a more robust clinical study.

Matched MeSH terms: Receptors, Adrenergic, alpha-2
In vitro functional evaluation of isolaureline, dicentrine and glaucine enantiomers at 5-HT2 and α1 receptors

Heng HL, Chee CF, Thy CK, Tee JT, Chin SP, Herr DR, et al.

Chem Biol Drug Des, 2019 02;93(2):132-138.
PMID: 30216681 DOI: 10.1111/cbdd.13390

Compounds with activity at serotonin (5-hydroxytryptamine) 5-HT2 and α1 adrenergic receptors have potential for the treatment of central nervous system disorders, drug addiction or overdose. Isolaureline, dicentrine and glaucine enantiomers were synthesized, and their in vitro functional activities at human 5-HT2 and adrenergic α1 receptor subtypes were evaluated. The enantiomers of isolaureline and dicentrine acted as antagonists at 5-HT2 and α1 receptors with (R)-isolaureline showing the greatest potency (pKb = 8.14 at the 5-HT2C receptor). Both (R)- and (S)-glaucine also antagonized α1 receptors, but they behaved very differently to the other compounds at 5-HT2 receptors: (S)-glaucine acted as a partial agonist at all three 5-HT2 receptor subtypes, whereas (R)-glaucine appeared to act as a positive allosteric modulator at the 5-HT2A receptor.

Matched MeSH terms: Receptors, Adrenergic, alpha-1/genetics; Receptors, Adrenergic, alpha-1/metabolism*; Receptors, Adrenergic, alpha-1/chemistry
GPCRs through the keyhole: the role of protein flexibility in ligand binding to β-adrenoceptors

Emtage AL, Mistry SN, Fischer PM, Kellam B, Laughton CA

J Biomol Struct Dyn, 2016 Aug 17.
PMID: 27532213

G protein-coupled receptors (GPCRs) are proteins of pharmaceutical importance, with over 30% of all drugs in clinical use targeting them. Increasing numbers of X-ray crystal (XRC) structures of GPCRs offer a wealth of data relating to ligand binding. For the β-adrenoceptors (β-ARs), XRC structures are available for human β2- and turkey β1-subtypes, in complexes with a range of ligands. While these structures provide insight into the origins of ligand structure-activity relationships (SARs), questions remain. The ligands in all published complexed XRC structures lack extensive substitution, with no obvious way the ligand-binding site can accommodate β1-AR-selective antagonists with extended side-chains para- to the common aryloxypropanolamine pharmacophore. Using standard computational docking tools with such ligands generally returns poses that fail to explain known SARs. Application of our Active Site Pressurization (ASP) modelling method to β-AR XRC structures and homology models however, reveals a dynamic area in the ligand-binding pocket that, through minor changes in amino acid side chain orientations, opens a fissure between transmembrane (TM) helices H4 and H5, exposing intra-membrane space. This fissure, which we term the 'keyhole', is ideally located to accommodate extended moieties present in many high-affinity β1-AR-selective ligands; allowing the rest of the ligand structure to adopt a canonical pose in the orthosteric binding site. We propose the keyhole may be a feature of both β1- and β2-ARs, but that subtle structural differences exist between the two, contributing to subtype-selectivity. This has consequences for the rational design of future generations of subtype-selective ligands for these therapeutically important targets.

Matched MeSH terms: Receptors, Adrenergic, beta
Fulltext Association of beta 2 adrenoceptor gene polymorphisms in Malaysian hypertensive subjects

Komara M, Vasudevan R, Ismail P, Bakar SA, Pishva SR, Heidari F

Genet. Mol. Res., 2014;13(2):2939-48.
PMID: 24782128 DOI: 10.4238/2014.April.16.2

The sympathetic nervous system plays a major role in blood pressure regulation. Beta 2 (β2) adrenoceptor gene polymorphisms have been associated with hypertension in different populations with conflicting results. We examined the association of three common polymorphisms, Arg16Gly, Gln27Glu, and Thr164Ile, of the β2 adrenoceptor gene in Malaysian hypertensive subjects. A total of 160 hypertensive and control subjects were recruited. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and anthropometric measurements were obtained from each subject. Biochemical analyses of lipid profiles were conducted with an autoanalyzer. DNA samples were extracted from blood and buccal cells. Genotyping was accomplished with polymerase chain reaction-restriction fragment length polymorphism. SBP, DBP, body mass index, and biochemical factors all differed significantly between case and control subjects (P < 0.05). The genotype frequencies of Arg16Arg, Arg16Gly, and Gly16Gly were 22.5, 70, and 7.5% among cases and 33.1, 63.1, and 3.8% among controls, respectively. The genotype frequencies of Gln27Gln, Gln27Glu, and Glu27Glu among cases were 41.1, 50, and 1.9% compared to 77.5, 20.6, and 1.9% among controls, respectively. In this study, the Gln27Glu polymorphism was significantly associated with Malaysian hypertensive subjects (P < 0.05). Therefore, the Gln27Glu polymorphism of the β2 adrenoceptor could be a risk factor associated with hypertension among Malaysians.

Matched MeSH terms: Receptors, Adrenergic, beta-2/genetics*
Gender-dependent association of a β(2)-adrenergic gene variant with obesity parameters in Malaysian Malays

Apalasamy YD, Ming MF, Rampal S, Bulgiba A, Mohamed Z

Asia Pac J Public Health, 2015 Mar;27(2):NP154-65.
PMID: 22199155 DOI: 10.1177/1010539511430250

Recent findings have shown that the rs1042714 (Gln27Glu) single-nucleotide polymorphism (SNP) on the β2-adrenoceptor gene may predispose to obesity. The findings from other studies carried on different populations, however, have been inconsistent. The authors investigated the association between the rs1042714 SNP with obesity-related parameters. DNA of 672 Malaysian Malays was analyzed using real-time polymerase chain reaction. Univariate and multivariate linear regression analyses revealed significant associations between rs1042714 and diastolic blood pressure in the pooled Malaysian Malay subjects under additive and recessive models. After gender stratification, however, a significant association was found between the rs1042714 and triglyceride and the rs1042714 and log-transformed high-density lipoprotein cholesterol levels in Malaysian Malay men. No significant association was found between the SNP and log-transformed body mass index. This polymorphism may have an important role in the development of obesity-related traits in Malaysian Malays. Gender is an effect modifier for the effect of the rs1042714 polymorphism on obesity-related traits in Malaysian Malays.

Matched MeSH terms: Receptors, Adrenergic, beta-2/genetics*
Fulltext Investigation of the Adrenergic and Opioid Binding Affinities, Metabolic Stability, Plasma Protein Binding Properties, and Functional Effects of Selected Indole-Based Kratom Alkaloids

Obeng S, Kamble SH, Reeves ME, Restrepo LF, Patel A, Behnke M, et al.

J Med Chem, 2020 01 09;63(1):433-439.
PMID: 31834797 DOI: 10.1021/acs.jmedchem.9b01465

Selected indole-based kratom alkaloids were evaluated for their opioid and adrenergic receptor binding and functional effects, in vivo antinociceptive effects, plasma protein binding, and metabolic stability. Mitragynine, the major alkaloid in Mitragyna speciosa (kratom), had higher affinity at opioid receptors than at adrenergic receptors while the vice versa was observed for corynantheidine. The observed polypharmacology of kratom alkaloids may support its utilization to treat opioid use disorder and withdrawal.

Matched MeSH terms: Receptors, Adrenergic/metabolism
High-fructose feeding impacts on the adrenergic control of renal haemodynamics in the rat

Abdulla MH, Sattar MA, Johns EJ, Abdullah NA, Hye Khan MA, Rathore HA

Br J Nutr, 2012 Jan;107(2):218-28.
PMID: 21733307 DOI: 10.1017/S0007114511002716

The present study explored the hypothesis that a prolonged 8 weeks exposure to a high fructose intake suppresses adrenergic and angiotensin II (Ang II)-mediated vasoconstriction and is associated with a higher contribution of α1D-adrenoceptors. A total of thirty-two Sprague-Dawley rats received either 20 % fructose solution (FFR) or tap water (control, C) to drink ad libitum for 8 weeks. Metabolic and haemodynamic parameters were assessed weekly. The renal cortical vasoconstrictor responses to noradrenaline (NA), phenylephrine (PE), methoxamine (ME) and Ang II were determined in the presence and absence of BMY7378 (α1D-adrenoceptor antagonist). FFR had increased blood pressure, plasma levels of glucose, TAG and insulin. FFR expressed reduced renal vascular responses to adrenergic agonists and Ang II (NA: 50 %, PE: 50 %, ME, 65 %, Ang II: 54 %). Furthermore in the C group, the magnitude of the renal cortical vasoconstriction to all agonists was blunted in the presence of the low or high dose of BMY7378 (NA: 30 and 31 %, PE: 23 and 33 %, ME: 19 and 44 %, Ang II: 53 and 77 %), respectively, while in the FFR, vasoconstriction was enhanced to adrenergic agonists and reduced to Ang II (NA: 8 and 83 %, PE: 55 %, ME, 2 and 177 %, Ang II: 61 and 31 %). Chronic high fructose intake blunts vascular sensitivity to adrenergic agonists and Ang II. Moreover, blocking of the α1D-adrenoceptor subtype results in enhancement of renal vasoconstriction to adrenergic agonists, suggesting an inhibitory action of α1D-adrenoceptors in the FFR. α1D-Adrenoceptors buffer the AT1-receptor response in the renal vasculature of normal rats and fructose feeding suppressed this interaction.

Matched MeSH terms: Receptors, Adrenergic, alpha-1/metabolism*; Receptors, Adrenergic, alpha-1/chemistry
Evidence for the role of α1A-adrenoceptor subtype in the control of renal haemodynamics in fructose-fed Sprague-Dawley rat

Abdulla MH, Sattar MA, Johns EJ, Abdullah NA, Khan MA

Eur J Nutr, 2011 Dec;50(8):689-97.
PMID: 21373947 DOI: 10.1007/s00394-011-0180-9

AIM: To explore the hypothesis that high fructose intake results in a higher functional contribution of α1A-adrenoceptors and blunts the adrenergically and angiotensin II (Ang II)-induced renal vasoconstriction.
METHODS: Twelve Sprague-Dawley rats received either 20% fructose solution [FFR] or tap water [C] to drink ad libitum for 8 weeks. The renal vasoconstrictor response to noradrenaline (NA), phenylephrine (PE), methoxamine (ME) and Ang II was determined in the presence and absence of 5-methylurapidil (5-MU) (α1A-adrenoceptor antagonist) in a three-phase experiment (pre-drug, low- and high-dose 5-MU). Data, mean ± SEM were analysed by ANOVA or Student's unpaired t-test with significance at P < 0.05.
RESULTS: FFR exhibited insulin resistance (HOMA index), hypertension and significant increases in plasma levels of glucose and insulin. All agonists caused dose-related reductions in cortical blood perfusion that were larger in C than in FFR while the magnitudes of the responses were progressively reduced with increasing doses of 5-MU in both C and FFR. The degree of 5-MU attenuation of the renal cortical vasoconstriction due to NA, ME and Ang II was significantly greater in the FFR compared to C.
CONCLUSIONS: Fructose intake for 8 weeks results in smaller vascular response to adrenergic agonists and Ang II. The α1A-adrenoceptor subtype is the functional subtype that mediates renal cortical vasoconstriction in control rats, and this contribution becomes higher due to fructose feeding.

Matched MeSH terms: Receptors, Adrenergic, alpha-1/drug effects*; Receptors, Adrenergic, alpha-1/metabolism*
Influence of high dietary sodium intake on the functional subtypes of alpha-adrenoceptors in the renal cortical vasculature of Wistar-Kyoto rats

Kazi RN, Munavvar AS, Abdullah NA, Khan AH, Johns EJ

Auton Autacoid Pharmacol, 2009 Jan;29(1-2):25-31.
PMID: 19302553 DOI: 10.1111/j.1474-8673.2009.00428.x

1 Increased renal vascular resistance is one renal functional abnormality that contributes to hypertension, and alpha(1)-adrenoceptors play a pivotal role in modulating this renal vascular resistance. This study investigates the functional contribution of alpha(1)-adrenoceptor subtypes in the renal cortical vasculature of Wistar-Kyoto rats on a normal sodium diet (WKYNNa) compared with those given saline to drink for 6 weeks (WKYHNa). 2 The renal cortical vascular responses to the adrenergic agonists noradrenaline (NA), methoxamine (ME) and phenylephrine (PE) were measured in WKYHNa and WKYNNa rats either in the absence (the control phase) or presence of chloroethylclonidine (CEC), an alpha(1B)-adrenoceptor antagonist, 5-methylurapidil (5-MeU), an alpha(1A) antagonist, or BMY7378, an alpha(1D) antagonist. 3 Results showed a greater renal cortical vascular sensitivity to NA, PE and ME in the WKYHNa compared with WKYNNa rats (P < 0.05). Moreover, 5-MeU and BMY7378 attenuated adrenergically induced renal cortical vasoconstriction in WKYHNa and WKYNNa rats; this response was largely blunted in CEC-treated WKYHNa rats (all P < 0.05) but not in CEC-treated WKYNNa rats. 4 The data suggest that irrespective of dietary sodium content, in Wistar-Kyoto rats alpha(1A)- and alpha(1D)-subtypes are the major alpha(1)-adrenoceptors in renal cortical vasculature; however, there appears to be a functional involvement of alpha(1B)-adrenoceptors in the WKYHNa rats.

Matched MeSH terms: Receptors, Adrenergic, alpha-1/drug effects*; Receptors, Adrenergic, alpha-1/physiology*
Alpha1A- and alpha1D-adrenoceptors are the major functional subtypes of renal alpha1-adrenoceptors in streptozotocin-induced diabetic and normal Sprague-Dawley rats

Armenia, Sattar MA, Abdullah NA, Khan MA, Johns EJ

Auton Autacoid Pharmacol, 2008 Jan;28(1):1-10.
PMID: 18257746 DOI: 10.1111/j.1474-8673.2007.00412.x

1 The present study investigated the effect of streptozotocin-induced diabetes on alpha(1)-adrenoceptor subtypes in rat renal resistance vessels. 2 Studies on renal haemodynamics were carried out 7 days after the last streptozotocin. Changes in renal blood flow were recorded in response to electrical stimulation of the renal nerve (RNS) and a range of adrenergic agonists; noradrenaline (NA), phenylephrine (PE) and methoxamine (MTX), either in the absence or the presence of nitrendipine (Nit), 5-methylurapidil (MEU), chlorethylclonidine (CEC) or BMY 7378. 3 In non-diabetic animals, Nit, MEU and BMY 7378 significantly attenuated renal vasoconstriction induced by adrenergic agonists, while CEC showed a significant accentuation in RNS-induced responses without having a significant effect on responses to adrenergic agonists. In diabetic rats, renal vasoconstriction was also significantly reduced in Nit-, MEU- and BMY 7378-treated groups and CEC potentiated RNS-induced contractions caused a change similar to that observed in non-diabetic rats. BMY 7378 significantly (P < 0.05) attenuated the PE- and MTX-induced vasoconstrictions but did not cause any significant (P > 0.05) alteration in the RNS- and NA-induced responses. 4 The results showed functional co-existence of alpha(1A)- and alpha(1D)-adrenoceptors in the renal vasculature of SD rats irrespective of the presence of diabetes. A possible minor contribution of prejunctional alpha-adrenoceptor subtype has also been suggested in either experimental group, particularly possible functional involvement of alpha(1B)-adrenoceptor subtypes in non-diabetic SD rats.

Matched MeSH terms: Receptors, Adrenergic, alpha-1/drug effects; Receptors, Adrenergic, alpha-1/metabolism*
Cisplatin-induced nephrotoxicity causes altered renal hemodynamics in Wistar Kyoto and spontaneously hypertensive rats: role of augmented renal alpha-adrenergic responsiveness

Hye Khan MA, Abdul Sattar M, Abdullah NA, Johns EJ

Exp. Toxicol. Pathol., 2007 Nov;59(3-4):253-60.
PMID: 17764917

The pathogenesis of cisplatin-induced renal failure is related to reduced renal blood flow due to severe tubular damage and enhanced renovascular resistance. It is also known that alpha(1)-adrenoceptors, the major subtype of alpha-adrenoceptors in renal vasculature play the pivotal role in regulating renal hemodynamics. With this background, we have hypothesized that the altered renal hemodynamics and enhanced renovascular resistance in cisplatin-induced renal failure might be caused by the altered alpha-adrenergic responsiveness with a possible involvement of alpha(1)-adrenoceptors in the renal vasculature. In a unique experimental approach with anesthetized rats, this study has therefore examined if there is any shift in the renovascular responsiveness to renal nerve stimulation and a series of alpha-adrenergic agonists in Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats with cisplatin-induced renal failure in comparison with their body weight-matched normal controls. Thirty-two male rats of both WKY (n=16) and SHR (n=16) origin with body weight 236+/-7.9 g received cisplatin (5mg/kg i.p.). The renal failure was confirmed in terms of significantly reduced renal blood flow, reduced creatinine clearance, increased fractional excretion of sodium, increased kidney index (all P<0.05) and tubular damage. After 7 days of cisplatin, the overnight fasted rats were anesthetized (sodium pentobarbitone, 60 mg/kg i.p.) and renal vasoconstrictor experiments were done. The changes in the vasoconstrictor responses were determined in terms of reductions in renal blood flow caused by electrical renal nerve stimulation or intrarenal administration of noradrenaline, phenylephrine and methoxamine. It was observed that in the cisplatin-treated renal failure WKY and SHR rats there were significant (all P<0.05) reductions in the renal blood flow along with significantly (P<0.05) higher renal adrenergic responsiveness as compared with their non-renal failure controls. The data showed that in the renal failure WKY and SHR rats, the altered renal hemodynamics might be caused by an augmented renal adrenergic responsiveness. The results obtained further led us to suggest that the augmented renal adrenergic responsiveness in the cisplatin-induced renal failure rats were possibly mediated by the alpha(1)-adrenoceptors.

Matched MeSH terms: Receptors, Adrenergic, alpha-1/drug effects*; Receptors, Adrenergic, alpha-1/metabolism
Interaction between irbesartan, peroxisome proliferator-activated receptor (PPAR-γ), and adiponectin in the regulation of blood pressure and renal function in spontaneously hypertensive rats

Afzal S, Sattar MA, Johns EJ, Abdulla MH, Akhtar S, Hashmi F, et al.

J Physiol Biochem, 2016 Dec;72(4):593-604.
PMID: 27405250

Adiponectin exerts vasodilatory effects. Irbesartan, an angiotensin receptor blocker, possesses partial peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist activity and increases circulating adiponectin. This study explored the effect of irbesartan alone and in combination with adiponectin on blood pressure, renal hemodynamic excretory function, and vasoactive responses to angiotensin II and adrenergic agonists in spontaneously hypertensive rat (SHR). Irbesartan was given orally (30 mg/kg/day) for 28 days and adiponectin intraperitoneally (2.5 μg/kg/day) for last 7 days. Groups of SHR received either irbesartan or adiponectin or in combination. A group of Wistar Kyoto rats (WKY) served as controls. Metabolic data and plasma samples were taken on days 0, 21, and 28. In acute studies, the renal vasoconstrictor actions of angiotensin II (ANGII), noradrenaline (NA), phenylephrine (PE), and methoxamine (ME) were determined. SHR control rats had a higher mean blood pressure than the WKY (132 ± 7 vs. 98 ± 2 mmHg), lower plasma and urinary adiponectin, creatinine clearance, urine flow rate and sodium excretion, and oxidative stress markers compared to WKY (all P

Matched MeSH terms: Receptors, Adrenergic, alpha/genetics; Receptors, Adrenergic, alpha/metabolism
Functional subtypes of renal alpha1-adrenoceptor in spontaneously hypertensive rats with streptozotocin-induced experimental diabetic nephropathy

Khan MA, Sattar MA, Abdullah NA, Abdulla MH, Salman IM, Kazi RN, et al.

Kidney Blood Press Res, 2009;32(5):349-59.
PMID: 19844130 DOI: 10.1159/000249149

This study investigated the impact of hypertension combined with diabetic nephropathy on rat renal alpha(1)-adrenoceptor subtype composition.

Matched MeSH terms: Receptors, Adrenergic, alpha-1/classification*; Receptors, Adrenergic, alpha-1/metabolism*
Association of ADRA2A and MTHFR gene polymorphisms with weight loss following antipsychotic switching to aripiprazole or ziprasidone

Roffeei SN, Reynolds GP, Zainal NZ, Said MA, Hatim A, Aida SA, et al.

Hum Psychopharmacol, 2014 Jan;29(1):38-45.
PMID: 24424705 DOI: 10.1002/hup.2366

Various genetic polymorphisms have been reported to be associated with antipsychotic-induced weight gain. In this study, we aimed to determine whether risk polymorphisms in 12 candidate genes are associated with reduction in body mass index (BMI) of patients following switching of antipsychotics to aripiprazole or ziprasidone.

Matched MeSH terms: Receptors, Adrenergic, alpha-2/genetics*
Fulltext Effect of renal sympathetic nerve on adrenergically and angiotensin II-induced renal vasoconstriction in normal Wistar-Kyoto rats

Abdulla MH, Sattar MA, Abdullah NA, Khan AH, Anand Swarup KR, Rathore HA, et al.

Ups. J. Med. Sci., 2011 Mar;116(1):18-25.
PMID: 21047287 DOI: 10.3109/03009734.2010.526723

This study examined the effect of renal sympathetic innervation on adrenergically and angiotensin II (Ang II)-induced renal vasoconstriction in Wistar-Kyoto (WKY) rats.

Matched MeSH terms: Receptors, Adrenergic, alpha-1/physiology
Fulltext Cystathione gamma lyase/Hydrogen Sulphide Pathway Up Regulation Enhances the Responsiveness of α1A and α1B-Adrenoreceptors in the Kidney of Rats with Left Ventricular Hypertrophy

Ahmad A, Sattar MA, Azam M, Abdulla MH, Khan SA, Hashmi F, et al.

PLoS One, 2016;11(5):e0154995.
PMID: 27191852 DOI: 10.1371/journal.pone.0154995

The purpose of the present study was to investigate the interaction between H2S and NO (nitric oxide) in the kidney and to evaluate its impact on the functional contribution of α1A and α1B-adrenoreceptors subtypes mediating the renal vasoconstriction in the kidney of rats with left ventricular hypertrophy (LVH). In rats the LVH induction was by isoprenaline administration and caffeine in the drinking water together with intraperitoneal administration of H2S. The responsiveness of α1A and α1B to exogenous noradrenaline, phenylephrine and methoxaminein the absence and presence of 5-methylurapidil (5-MeU) and chloroethylclonidine (CEC) was studied. Cystathione gamma lyase (CSE), cystathione β synthase (CBS), 3-mercaptopyruvate sulphar transferase (3-MST) and endothelial nitric oxide synthase (eNOS) were quantified. There was significant up regulation of CSE and eNOS in the LVH-H2S compared to the LVH group (P<0.05). Baseline renal cortical blood perfusion (RCBP) was increased (P<0.05) in the LVH-H2S compared to the LVH group. The responsiveness of α1A-adrenergic receptors to adrenergic agonists was increased (P<0.05) after administration of low dose 5-Methylurapidil in the LVH-H2S group while α1B-adrenergic receptors responsiveness to adrenergic agonists were increased (P<0.05) by both low and high dose chloroethylclonidine in the LVH-H2S group. Treatment of LVH with H2S resulted in up-regulation of CSE/H2S, CBS, and 3-MST and eNOS/NO/cGMP pathways in the kidney. These up regulation of CSE/H2S, CBS, and 3-MST and eNOS/NO/cGMP pathways enhanced the responsiveness of α1A and α1B-adrenoreceptors subtypes to adrenergic agonists in LVH-H2S. These findings indicate an important role for H2S in modulating deranged signalling in the renal vasculature resulting from LVH development.

Matched MeSH terms: Receptors, Adrenergic, alpha/metabolism*
Vasorelaxant and chemical fingerprint studies of Citrus reticulatae pericarpium extracts

Tan CS, Loh YC, Ch'ng YS, Ng CH, Yeap ZQ, Ahmad M, et al.

J Ethnopharmacol, 2019 Mar 25;232:135-144.
PMID: 30543913 DOI: 10.1016/j.jep.2018.12.014

ETHNOPHARMACOLOGICAL RELEVANCE: Citrus reticulatae Pericarpium (Chen pi) was widely used as an important ingredient in the prescription of TCM to treat phlegm fluid retention type hypertension. Since Chen pi is involved in treatment as antihypertensive TCM formula, we have reasonable expectation in believing that it might possess vasorelaxant activity.
AIM OF THE STUDY: This study is designed to investigate the vasorelaxant effect of Chen pi and to study its pharmacology effects.
MATERIALS AND METHODS: The vasorelaxant effect of water extract of Chen pi (CRW) were evaluated on thoracic aortic rings isolated from Sprague Dawley rats. The fingerprint of Chen pi and the extracts were developed with quantification of hesperidin content by HPTLC.
RESULTS: CRW exhibited the strongest vasorelaxant activity. CRW caused the relaxation of the phenylephrine pre-contracted aortic rings in the presence and absence of endothelium as well as in potassium chloride pre-contracted endothelium-intact aortic ring. The incubation of propranolol (β-adrenergic receptor blocker), atropine (muscarinic receptor blocker), Nω-nitro-L-arginine methyl ester (NO synthase inhibitor), ODQ (sGC inhibitor), indomethacin (COX inhibitor), 4-aminopyridine (KV blocker), barium chloride (Kir blocker), and glibenclamide (KATP blocker) significantly reduced the vasorelaxant effects of CRW. CRW was also found to be active in reducing Ca2+ releases from the sarcoplasmic reticulum and suppressing the voltage-operated calcium channels.
CONCLUSION: The vasorelaxant effect of CRW on rat aorta involves NO/sGC, calcium and potassium channels, muscarinic and β-adrenergic receptors.

Matched MeSH terms: Receptors, Adrenergic, beta/physiology
Underlying mechanism of vasorelaxant effect exerted by 3,5,7,2',4'-pentahydroxyflavone in rats aortic ring

Tew WY, Tan CS, Asmawi MZ, Yam MF

Eur J Pharmacol, 2020 Aug 05;880:173123.
PMID: 32335091 DOI: 10.1016/j.ejphar.2020.173123

Morin (3,5,7,2',4'-pentahydroxyflavone) is a yellow coloured natural flavonoid found in plants of the Moraceae family. This favonoid is easily sources from readily available fruits, vegetables and eve certain beverages. Among the sources that was identified, it is clear that morin is most abundantly found in almond, old fustic, Indian guava, and Osage orange. Multiple studies have suggested that morin has multiple therapeutic actions and possess potential to be a functional potent drug. Previous studies demonstrated that morin is capable of resolving deoxycorticosterone acetate-salt-induced hypertension and possess strong vasorelaxant properties. However, the exact mechanisms remains unknown. Therefore, this study is designed to investigate the in vitro mechanism of morin-induced vasorelaxant effects. The underlying mechanisms of morin's vasorelaxant activities were evaluated on thoracic aortic rings isolated from Sprague-Dawley rats. Results from the study demonstrated morin causing vasodilatory reaction in phenylephrine and potassium chloride pre-contracted endothelium-intact aortic rings with the effect being significantly affected in endothelium-denuded aortic rings. Pre-incubation of the aortic rings with ODQ (selective cGMP-independent sGC inhibitor), indomethacin (nonselective COX inhibitor), L-NAME (endothelial nitric oxide inhibitor), propranolol (β2-adrenegic receptors blocker), and atropine (muscarinic receptors blocker) significantly reduced the vasorelaxant effect of morin. It was also found to be able to reduce the intracellular calcium level by blocking VOCC and calcium intake from the extracellular environment and the intracellular release of calcium from the sarcoplasmic reticulum. The present study showed that the vasorelaxant effect of morin potentially involves the NO/sGC, muscarinic receptors, β2-adrenegic receptors, and calcium channels.

Matched MeSH terms: Receptors, Adrenergic, beta-2/physiology
Identification of adenylate cyclase-coupled beta-adrenergic receptors with radiolabeled beta-adrenergic antagonists

Lefkowitz RJ

Biochem Pharmacol, 1975 Sep 15;24(18):1651-8.
PMID: 11
Matched MeSH terms: Receptors, Adrenergic/drug effects*
Fulltext Alpha1B-adrenoceptors mediate adrenergically-induced renal vasoconstrictions in rats with renal impairment

Khan MA, Sattar MA, Abdullah NA, Johns EJ

Acta Pharmacol Sin, 2008 Feb;29(2):193-203.
PMID: 18215348 DOI: 10.1111/j.1745-7254.2008.00727.x

This study examined whether alpha1B-adrenoceptors are involved in mediating adrenergically-induced renal vasoconstrictor responses in rats with pathophysiological and normal physiological states.

Matched MeSH terms: Receptors, Adrenergic, alpha-1/physiology*

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