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Drumm BT, Gupta N, Mircea A, Griffin CS. Cells and ionic conductances contributing to spontaneous activity in bladder and urethral smooth muscle. J Physiol 2024. [PMID: 39323077 DOI: 10.1113/jp284744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 09/02/2024] [Indexed: 09/27/2024] Open
Abstract
Smooth muscle organs of the lower urinary tract comprise the bladder detrusor and urethral wall, which have a reciprocal contractile relationship during urine storage and micturition. As the bladder fills with urine, detrusor smooth muscle cells (DSMCs) remain relaxed to accommodate increases in intravesical pressure while urethral smooth muscle cells (USMCs) sustain tone to occlude the urethral orifice, preventing leakage. While neither organ displays coordinated regular contractions as occurs in small intestine, lymphatics or renal pelvis, they do exhibit patterns of rhythmicity at cellular and tissue levels. In rabbit and guinea-pig urethra, electrical slow waves are recorded from USMCs. This activity is linked to cells expressing vimentin, c-kit and Ca2+-activated Cl- channels, like interstitial cells of Cajal in the gastrointestinal tract. In mouse, USMCs are rhythmically active (firing propagating Ca2+ waves linked to contraction), and this cellular rhythmicity is asynchronous across tissues and summates to form tone. Experiments in mice have failed to demonstrate a voltage-dependent mechanism for regulating this rhythmicity or contractions in vitro, suggesting that urethral tone results from an intrinsic ability of USMCs to 'pace' their own Ca2+ mobilization pathways required for contraction. DSMCs exhibit spontaneous transient contractions, increases in intracellular Ca2+ and action potentials. Consistent across numerous species, including humans, this activity relies on voltage-dependent Ca2+ influx in DSMCs. While interstitial cells are present in the bladder, they do not 'pace' the organ in an excitatory manner. Instead, specialized cells (PDGFRα+ interstitial cells) may 'negatively pace' DSMCs to prevent bladder overexcitability.
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Affiliation(s)
- Bernard T Drumm
- Smooth Muscle Research Centre, Department of Life & Health Science, Dundalk Institute of Technology, Dundalk, Ireland
| | - Neha Gupta
- Smooth Muscle Research Centre, Department of Life & Health Science, Dundalk Institute of Technology, Dundalk, Ireland
| | - Alexandru Mircea
- Smooth Muscle Research Centre, Department of Life & Health Science, Dundalk Institute of Technology, Dundalk, Ireland
| | - Caoimhin S Griffin
- Smooth Muscle Research Centre, Department of Life & Health Science, Dundalk Institute of Technology, Dundalk, Ireland
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Drumm BT, Thornbury KD, Hollywood MA, Sergeant GP. Role of Ano1 Ca 2+-activated Cl - channels in generating urethral tone. Am J Physiol Renal Physiol 2021; 320:F525-F536. [PMID: 33554780 DOI: 10.1152/ajprenal.00520.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Urinary continence is maintained in the lower urinary tract by the contracture of urethral sphincters, including smooth muscle of the internal urethral sphincter. These contractions occlude the urethral lumen, preventing urine leakage from the bladder to the exterior. Over the past 20 years, research on the ionic conductances that contribute to urethral smooth muscle contractility has greatly accelerated. A debate has emerged over the role of interstitial cell of Cajal (ICC)-like cells in the urethra and their expression of Ca2+-activated Cl- channels encoded by anoctamin-1 [Ano1; transmembrane member 16 A (Tmem16a) gene]. It has been proposed that Ano1 channels expressed in urethral ICC serve as a source of depolarization for smooth muscle cells, increasing their excitability and contributing to tone. Although a clear role for Ano1 channels expressed in ICC is evident in other smooth muscle organs, such as the gastrointestinal tract, the role of these channels in the urethra is unclear, owing to differences in the species (rabbit, rat, guinea pig, sheep, and mouse) examined and experimental approaches by different groups. The importance of clarifying this situation is evident as effective targeting of Ano1 channels may lead to new treatments for urinary incontinence. In this review, we summarize the key findings from different species on the role of ICC and Ano1 channels in urethral contractility. Finally, we outline proposals for clarifying this controversial and important topic by addressing how cell-specific optogenetic and inducible cell-specific genetic deletion strategies coupled with advances in Ano1 channel pharmacology may clarify this area in future studies.NEW & NOTEWORTHY Studies from the rabbit have shown that anoctamin-1 (Ano1) channels expressed in urethral interstitial cells of Cajal (ICC) serve as a source of depolarization for smooth muscle cells, increasing excitability and tone. However, the role of urethral Ano1 channels is unclear, owing to differences in the species examined and experimental approaches. We summarize findings from different species on the role of urethral ICC and Ano1 channels in urethral contractility and outline proposals for clarifying this topic using cell-specific optogenetic approaches.
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Affiliation(s)
- Bernard T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Keith D Thornbury
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Mark A Hollywood
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Gerard P Sergeant
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
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Conlon K, Christy C, Westbrook S, Whitlock G, Roberts L, Stobie A, McMurray G. Pharmacological properties of 2-((R-5-chloro-4-methoxymethylindan-1-yl)-1H-imidazole (PF-3774076), a novel and selective alpha1A-adrenergic partial agonist, in in vitro and in vivo models of urethral function. J Pharmacol Exp Ther 2009; 330:892-901. [PMID: 19498105 DOI: 10.1124/jpet.109.154963] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
2-((R-5-chloro-4-methoxymethyl-indan-1-yl)-1H-imidazole (PF-3774076) is a central nervous system (CNS) penetrant, potent, selective, partial agonist at the human alpha1(A)-adrenoceptor, demonstrating efficacy and selectivity in a range of binding and functional assays. In vivo, PF-3774076 increases peak urethral pressure in anesthetized female dogs in a dose-dependent manner, inducing changes in both the proximal and distal portions of the urethra via a central mechanism of action. The profile of this compound suggests that a CNS penetrant partial agonist at the alpha1(A)-adrenoceptor may offer significant benefit in stress urinary incontinence (SUI). However, despite partial agonism at the alpha1(A)-adrenoceptor and selectivity over alpha1(B)- and alpha1(D)-adrenoceptors, PF-3774076 did not offer the necessary degree of separation over cardiovascular events when assessed in in vivo models of cardiovascular function. This may be due to activation of both peripheral and central alpha1(A)-adrenoceptors. These data indicate that although central, partial alpha1(A)-agonists may offer significant benefit in the treatment of SUI, it may not be possible to achieve the desired level of urethral selectivity over cardiovascular events with this class of agent.
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Affiliation(s)
- Kelly Conlon
- Department of Genitourinary Biology, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent, CT13 9NJ.
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Alberts P, Johansson BG, McArthur RA. Characterization of energy expenditure in rodents by indirect calorimetry. ACTA ACUST UNITED AC 2008; Chapter 9:Unit9.23D. [PMID: 18428652 DOI: 10.1002/0471142301.ns0923ds36] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The need for treatment of obesity and obesity-related diseases, such as type 2 diabetes, has been intensified by the epidemic rise of obesity. Recent advances make possible continuous monitoring of metabolically relevant functions in animals to identify novel thermogenic and anorectic compounds. This unit describes non-invasive in vivo calorimetric assessment of energy expenditure using measurements of oxygen consumption and carbon dioxide production, complemented by telemetric monitoring of body core temperature and locomotor activity in mice and rats. Reference compounds are used to illustrate the determination of substance-specific parameters, such as the dose that produces the half-maximal effect (ED(50)), the maximal effect, as well as the time of onset and duration of compound action. Indirect calorimetry performed at different temperatures provides information on several other well-defined parameters, including resting metabolic rate, basal metabolic rate, lower critical temperature, temperature sensitivity, defended body temperature, and respiratory quotient.
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Bagot K, Chess-Williams R. Alpha1A/L-adrenoceptors mediate contraction of the circular smooth muscle of the pig urethra. ACTA ACUST UNITED AC 2006; 26:345-53. [PMID: 16968473 DOI: 10.1111/j.1474-8673.2006.00374.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Sympathetically mediated urethral tone is essential for the maintenance of continence and involves the activation of postjunctional alpha(1)-adrenoceptors. This study characterizes the alpha(1)-adrenoceptor subtypes responsible for mediating contraction of the urethral circular smooth muscle of the pig. The potency order of a number of agonists and the affinities of several receptor selective antagonists were determined on pig-isolated circular smooth muscle strips in the presence of cocaine (1 microm) and corticosterone (10 microm) to inhibit amine uptake and propranolol (1 microm) to antagonize beta-adrenoceptors. The potency order for agonists was N-[5-(4,5-dihydro-1H-imidazol-2yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulphonamide (A61603) > noradrenaline = phenylephrine = M6434 > methoxamine with pEC(50) values of 7.3, 5.8, 5.7, 5.6 and 5.0 respectively. 4 The alpha(1D)-adrenoceptor-selective antagonist 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4,5]decane-7,9-dione (BMY7378) caused rightward shifts of the concentration-response curves to noradrenaline, yielding a low affinity estimate (6.6) for the urethral receptor. The alpha(1A)-adrenoceptor-selective antagonists, RS100329 and 5-methylurapidil, gave relatively high affinity estimates (9.6 and 8.8 respectively) for this receptor. All three antagonists produced Schild plots with slopes close to unity but did reduce maximum responses at higher concentrations. Prazosin antagonized responses of the urethra to noradrenaline, yielding a mean affinity estimate of 9.0. Although the Schild plot for prazosin again had a slope of unity, this drug also reduced maximum responses to noradrenaline at all concentrations examined (10-100 nm). N-[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-alpha,alpha-dimethyl-1H-indole-3-ethanamide (RS17053), which discriminates between responses mediated via alpha(1A) (high affinity) and alpha(1L)-adrenoceptors (low affinity) at concentrations up to 3 microm, failed to antagonize responses of the urethra. 5 These results suggest that contraction of urethral circular smooth muscle in the pig is mediated via a single population of adrenoceptors with the pharmacological characteristics of the alpha(1A/L)-adrenoceptor, most probably the alpha(1L)-adrenoceptor.
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Affiliation(s)
- K Bagot
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
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Alberts P, Klingström G, Arrhenius‐Nyberg V, Larsson C, Sakariassen KS. A micro‐method for lipoprotein cholesterol profiles: Impact of CETP in KKA
y
mice. EUR J LIPID SCI TECH 2006. [DOI: 10.1002/ejlt.200500261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Pe¯teris Alberts
- Pharmacology, Department of Biology, Biovitrum, Stockholm, Sweden
| | | | | | - Catarina Larsson
- Pharmacology, Department of Biology, Biovitrum, Stockholm, Sweden
| | - Kjell S. Sakariassen
- Pharmacology, Department of Biology, Biovitrum, Stockholm, Sweden
- Present address: KellSa s.a.s., Str. Campo e Zampe 12, I‐13900 Biella, BI, Italy
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Bae JH, Jung PB, Lee JG. The effects of alpha1A-adrenoceptor antagonists on the urethral perfusion pressure of the female rat. BJU Int 2005; 96:1131-5. [PMID: 16225542 DOI: 10.1111/j.1464-410x.2005.05812.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To assess the effects of alpha(1A)-adrenoceptor antagonists on urethral perfusion pressure (UPP) in the female rate and their therapeutic potential for treating female bladder outlet obstruction (BOO). MATERIALS AND METHODS A cannula was inserted into the femoral arteries of female rats to administer tamsulosin (group I), doxazosin (group II) or phentolamine (group III) and to monitor systemic blood pressure. Tamsulosin was also administered to male rats (group IV). UPP and vesical pressures (Pves) were monitored using a triple-lumen catheter. RESULTS After administration of tamsulosin to group I the frequency of bladder contractions decreased significantly and the duration of minimal urethral relaxation with high-frequency oscillations (HFOs) was significantly prolonged. Except for mean arterial blood pressure (MAP), none of the variables in group I differed significantly from those in group II and group III. The change in MAP after tamsulosin treatment was significantly lower than after doxazosin or phentolamine. Except for the maximum Pves, which was significantly higher in males (group IV) than in females of group I, the UPP and Pves curves of male rats were similar to those of females before giving tamsulosin. The prolonged frequency and duration of HFO in group IV (with tamsulosin) were significantly different from those of females. CONCLUSIONS The alpha(1A)-adrenergic receptor may be a functional subtype in the female rat urethra. alpha(1A)-adrenoceptor antagonists prolonged the duration of HFOs and decreased the frequency of involuntary bladder contraction. It is possible that treatment with alpha(1A)-adrenoceptor antagonists would not only improve obstructive symptoms, but also ameliorate irritative symptoms by prolonging HFOs and the frequency of involuntary bladder contractions.
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Affiliation(s)
- Jae-Hyun Bae
- Department of Urology, Korea University College of Medicine, Seoul, Korea
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Alberts P, Johansson BG, McArthur RA. Measurement and Characterization of Energy Expenditure as a Tool in the Development of Drugs for Metabolic Diseases, such as Obesity and Diabetes. ACTA ACUST UNITED AC 2005; Chapter 5:Unit5.39. [DOI: 10.1002/0471141755.ph0539s28] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Flavahan NA. Phenylpropanolamine constricts mouse and human blood vessels by preferentially activating alpha2-adrenoceptors. J Pharmacol Exp Ther 2004; 313:432-9. [PMID: 15608085 DOI: 10.1124/jpet.104.076653] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Phenylpropanolamine (dl-norephedrine) was one of the most widely used therapeutic agents to act on the sympathetic nervous system. Because of concerns regarding incidents of stroke, its use as a nasal decongestant was discontinued. Although considered an alpha1-adrenergic agonist, the vascular adrenergic pharmacology of phenylpropanolamine was not fully characterized. Unlike most other circulations, the vasculature of the nasal mucosa is highly enriched with constrictor alpha2-adrenoceptors. Therefore, experiments were performed to determine whether phenylpropanolamine activates vascular alpha2-adrenoceptors. Mouse tail and mesenteric small arteries and human small dermal veins were isolated and analyzed in a perfusion myograph. The selective alpha1-adrenergic agonist phenylephrine caused constriction of tail and mesenteric arteries and human veins. The selective alpha2-adrenergic agonist UK14,304 [5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine] caused constriction in tail arteries and in human veins, but not mesenteric arteries. The lack of constriction to UK14,304 was also observed in endothelium-denuded mesenteric arteries. Phenylpropanolamine constricted both types of artery but was 62-fold more potent in tail arteries. In mesenteric arteries, constriction to phenylpropanolamine was not affected by the selective alpha2-adrenergic antagonist, rauwolscine (10(-7) M) but was abolished by the selective alpha1-adrenergic antagonist, prazosin (3 x 10(-7) M). In contrast, constriction to phenylpropanolamine in tail arteries and in human veins was inhibited by rauwolscine but not prazosin. Therefore, phenylpropanolamine is a preferential alpha2-adrenergic agonist. At low concentrations, it constricts blood vessels that express functional alpha2-adrenoceptors, whereas at much higher concentrations, phenylpropanolamine also activates vascular alpha1-adrenoceptors. This action likely contributed to phenylpropanolamine's therapeutic activity, namely constriction of the nasal vasculature.
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Affiliation(s)
- Nicholas A Flavahan
- DAvis Heart and Lung Research Institute, Ohio State University, Columbus OH 43210, USA.
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Blechman KM, Karch SB, Stephens BG. Demographic, pathologic, and toxicological profiles of 127 decedents testing positive for ephedrine alkaloids. Forensic Sci Int 2004; 139:61-9. [PMID: 14687775 DOI: 10.1016/j.forsciint.2003.09.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The relative toxicity of ephedra-containing dietary supplements is disputed. In order to ascertain the magnitude of the problem, we reviewed all autopsies in our Medical Examiner's jurisdiction, from 1994 to 2001, where ephedrine or any its isomers (E+) were detected. Toxicology testing results were tabulated and anatomic findings in E+ cases were compared to those in a control group of drug-free trauma victims. Of 127 E+ cases identified, 33 were due to trauma. Decedents were mostly male (80.3%) and mostly Caucasian (59%). Blood ephedrine concentrations were <0.49 mg/l in 50% of the cases, range 0.07-11.73 mg/l in trauma victims, and 0.02-12.35 mg/l in non-trauma cases. Norephedrine (NE) was present in the blood of 22.8% (mean of 1.81 mg/l, S.D.=3.14 mg/l) and in the urine of 36.2% (mean of 15.6 mg/l, S.D.=21.50mg/l). Pseudoephedrine (PE) was present in the blood of 6.3% (8/127). More than 88% (113/127) of the decedents also tested positive for other drugs, the most common being cocaine (or its metabolites) and morphine. The most frequent pathologic diagnoses were hepatic steatosis (27/127) and nephrosclerosis (22/127). Left ventricular hypertrophy was common, and coronary artery disease (CAD) detected in nearly one third of the cases. The most common findings in E+ deaths are those generally associated with chronic stimulant abuse, and abuse of other drugs was common in those with CAD. There were no cases of heat stroke or rhabdomyolysis. In most cases, norephedrine was not detected, suggesting it plays no role in ephedrine toxicity.
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Affiliation(s)
- Keith M Blechman
- New York University School of Medicine, 200 East 33rd Street, Apt 19-I, New York, NY 10016, USA
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Blue DR, Daniels DV, Gever JR, Jett MF, O'Yang C, Tang HM, Williams TJ, Ford APDW. Pharmacological characteristics of Ro 115-1240, a selective alpha1A/1L-adrenoceptor partial agonist: a potential therapy for stress urinary incontinence. BJU Int 2004; 93:162-70. [PMID: 14678390 DOI: 10.1111/j.1464-410x.2004.04577.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To describe the preclinical pharmacology of Ro 115-1240, a peripherally acting selective alpha1A/1L-adrenoceptor (AR) partial agonist, compared with the alpha1A/1L-AR full agonist amidephrine, as AR agonists have some utility in the treatment of stress urinary incontinence (SUI) but are limited by undesirable cardiovascular and central nervous system side-effects. RESULTS In radioligand-binding studies Ro 115-1240 had greater affinity for alpha1A than for alpha1B and alpha1D subtypes. The potency and intrinsic activity of amidephrine and Ro 115-1240 relative to noradrenaline were determined in native and cell-based assays using human recombinant alpha1-ARs; they acted as selective alpha1A/1L-AR full and partial agonists, respectively. In anaesthetized micropigs and rabbits, amidephrine and Ro 115-1240 produced non-selective, dose-dependent increases in intraurethral and arterial blood pressures but the magnitude of the pressure increases evoked by Ro 115-1240 were about a third of those with amidephrine. In conscious micropigs both agents produced dose-dependent increases in urethral tension. Again, the magnitude of the urethral response to Ro 115-1240 was about a third of that with amidephrine. More importantly, only amidephrine produced dose-dependent increases in blood pressure and decreases in heart rate. Ro 115-1240 produced a maximum increase in urethral tension with no effect on blood pressure or heart rate. CONCLUSION These results show that by combining selectivity for the alpha1A/1L-AR subtype with a reduction in intrinsic agonist efficacy, Ro 115-1240 has reduced haemodynamic effects while retaining to some degree the contractile effects on urethral smooth muscle. These studies indicate that Ro 115-1240 may be useful as a novel treatment for SUI.
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Affiliation(s)
- D R Blue
- Roche Palo Alto, Palo Alto, CA, USA.
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Speake JD, Navas F, Bishop MJ, Garrison DT, Bigham EC, Hodson SJ, Saussy DL, Liacos JA, Irving PE, Sherman BW. 2-(Anilinomethyl)imidazolines as alpha1 adrenergic receptor agonists: alpha1a subtype selective 2'-heteroaryl compounds. Bioorg Med Chem Lett 2003; 13:1183-6. [PMID: 12643939 DOI: 10.1016/s0960-894x(03)00050-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The structure-activity relationship of 2'-pyrrole, pyrazole and triazole substituted 2-(anilinomethyl)imidazolines as alpha(1) adrenergic agonists was investigated. The size and orientation of substituents, as well as the position of the heteroatoms, were found to have a profound effect on the potency and selectivity of the molecules. Potent alpha(1A) subtype selective agonists have been identified.
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Affiliation(s)
- Jason D Speake
- GlaxoSmithKline, 5Moore Drive, Research Triangle Park, NC 27709, USA.
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Hodson SJ, Bigham EC, Garrison DT, Gobel MJ, Irving PE, Liacos JA, Navas F, Saussy DL, Sherman BW, Speake JD, Bishop MJ. Alpha(1)-adrenoceptor activation: a comparison of 4-(anilinomethyl)imidazoles and 4-(phenoxymethyl)imidazoles to related 2-imidazolines. Bioorg Med Chem Lett 2002; 12:3449-52. [PMID: 12419381 DOI: 10.1016/s0960-894x(02)00753-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Literature reports suggest that disruption of an interhelical salt bridge is critical for alpha(1)-adrenoceptor activation, and the basic amine found in adrenergic receptor ligands is responsible for the disruption. Novel 4-(anilinomethyl)imidazoles and 4-(phenoxymethyl)imidazoles are agonists of the cloned human alpha(1)-adrenoceptors in vitro, and potent, selective alpha(1A)-adrenoceptor agonists have been identified in this series. These imidazoles demonstrate similar potencies and alpha(1)-subtype selectivities as the corresponding 2-substituted imidazolines. The extremely close SAR suggests that, in spite of the large difference in basicity, these imidazoles and imidazolines may establish the same interactions to activate alpha(1)-adrenoceptors.
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Affiliation(s)
- Stephen J Hodson
- GlaxoSmithKline Research and Development, Research Triangle Park, NC 27709, USA
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Modiri AR, Vasänge M, Alberts P, Jossan SS, Sundquist S, Gillberg PG. Characterization of a new muscarinic receptor antagonist PNU-171990 in guinea pig, cat and human smooth muscle. Eur J Pharmacol 2002; 451:171-5. [PMID: 12231388 DOI: 10.1016/s0014-2999(02)02227-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The present study was done to characterize a new compound, PNU-171990, 2-diisopropyl aminoethyl 1-phenylcyclopentane carboxylate hydrochloride, with functional smooth muscle selectivity at least as high as tolterodine. In vitro homogenates of guinea pig cerebral cortex, parotid gland, heart, urinary bladder, and Chinese hamster ovary (CHO) cells expressing human muscarinic m(1)-m(5) receptors PNU-171990 did not show selectivity for any subtype (pK(i), 7.72-8.64). PNU-171990 caused a parallel shift in the concentration-response curve for carbachol-induced contraction of smooth muscle from guinea pig bladder (pK(B), 7.65), guinea pig ileum (pK(B), 8.48), and human ileum (pK(B), 7.10). In vivo PNU-171990 inhibited urinary bladder contraction with a significantly lower ID(50) than on the salivary secretion (206 and 706 nmol/kg, respectively, P<0.05). In conclusion, PNU-171990 is a competitive and potent muscarinic receptor antagonist in vitro with a numerically better selectivity ratio for the bladder contraction over salivation in vivo than tolterodine.
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Affiliation(s)
- Ali-Reza Modiri
- Department of Biology, Biovitrum, UF5-1, SE-751 37, Uppsala, Sweden.
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Modiri AR, Alberts P, Gillberg PG. Effect of muscarinic antagonists on micturition pressure measured by cystometry in normal, conscious rats. Urology 2002; 59:963-8. [PMID: 12031395 DOI: 10.1016/s0090-4295(02)01535-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To establish an in vivo model to screen new muscarinic antagonists for the treatment of overactive urinary bladder and to calculate the respective ID(50) values. METHODS The conscious rat cystometry model was modified to determine a complete dose-response curve in each animal. Spontaneous micturition was induced by infusion of room-temperature saline into rat bladders at a constant rate of 12 mL/hr. Cumulative doses of muscarinic antagonists administered in the femoral vein caused dose-dependent inhibition of the urinary bladder contraction measured as the micturition pressure. In addition, the in vitro pK(B) values for atropine, PNU-200577 (DD01), tolterodine, oxybutynin, and terodiline were determined in carbachol-contracted rat bladder strips. RESULTS The rank order of the in vivo ID(50) values were atropine (14 +/- 4 nmol/kg), PNU-200577 (22 +/- 12 nmol/kg), tolterodine (94 +/- 20 nmol/kg), oxybutynin (175 +/- 89 nmol/kg), darifenacin (236 +/- 144 nmol/kg), desethyloxybutynin (313 +/- 209 nmol/kg), propiverine (4561 +/- 2079 nmol/kg), and terodiline (18,339 +/- 5348 nmol/kg). Tolterodine and PNU-200577 caused a parallel shift of the in vitro concentration-response curve to the right and did not alter the maximal contraction. The ID(50) values correlated significantly with the in vitro rat pK(B) and human bladder pA(2) values. CONCLUSIONS The present results suggest that the rat cystometry model can be used in in vivo screening for new muscarinic antagonists.
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Bishop MJ, Barvian KA, Berman J, Bigham EC, Garrison DT, Gobel MJ, Hodson SJ, Irving PE, Liacos JA, Navas F, Saussy DL, Speake JD. alpha(1)-Adrenoceptor agonists: the identification of novel alpha(1A )subtype selective 2'-heteroaryl-2-(phenoxymethyl)imidazolines. Bioorg Med Chem Lett 2002; 12:471-5. [PMID: 11814822 DOI: 10.1016/s0960-894x(01)00764-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Novel 2'-heteroaryl-2-(phenoxymethyl)imidazolines have been identified as potent agonists of the cloned human alpha(1)-adrenoceptors in vitro. The nature of the 2'-heteroaryl group can have significant effects on the potency, efficacy, and subtype selectivity in this series. alpha(1A) Subtype selective agonists have been identified.
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Affiliation(s)
- Michael J Bishop
- GlaxoSmithKline Research and Development, 5 Moore Drive, Research Triangle Park, NC 27709,
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Bishop MJ, Berman J, Bigham EC, Garrison DT, Gobel MJ, Hodson SJ, Irving PE, Liacos JA, Minick DJ, Navas F, Saussy DL, Speake JD. 2-(Anilinomethyl)imidazolines as alpha(1)-adrenoceptor agonists: the identification of alpha(1A) subtype selective 2'-carboxylic acid esters and amides. Bioorg Med Chem Lett 2001; 11:2871-4. [PMID: 11597419 DOI: 10.1016/s0960-894x(01)00569-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
2-(Anilinomethyl)imidazolines with 2'-esters or 2'-amides are potent agonists of the cloned human alpha(1)-adrenoceptors in vitro. The size and shape of the ortho substituent can have significant effects on the potency, efficacy, and subtype selectivity of these 2-(anilinomethyl)imidazolines. alpha(1A)-subtype selective agonists have been identified.
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Affiliation(s)
- M J Bishop
- GlaxoSmithKline, 5Moore Drive, Research Triangle Park, NC 27709, USA.
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Abstract
This review focuses on what we consider to be the most important findings of the last year relating to the smooth muscle of the lower urogenital system and the different levels of regulation that control its contraction and relaxation. One level is through modulation of the smooth muscle itself or its environment. Recent findings examining myosin isoform composition and collagen content as well as mechanisms that appear to be involved in inducing hyperplasia/hypertrophy of smooth muscle are described. Another method of regulation is via calcium-dependent phosphorylation of the regulatory light chain of myosin, which increases its activity. Interesting results indicating an uncoupling of force from calcium in the bladder are discussed. A third level of regulation is pharmacologic. Thus, the most recent findings related to receptor subtypes, including muscarinic, endothelin, alpha-adrenergic and nicotinic receptors, are presented. In addition, the effects of diabetes, incontinence, and partial bladder outlet obstruction on these modes of contractile regulation are also discussed.
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Affiliation(s)
- M E DiSanto
- Division of Urology, 3010 Ravdin Courtyard, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
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