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Leitão Junior AS, Campos RM, Cerqueira JBG, Fonteles MC, Santos CF, de Nucci G, Sousa EHS, Lopes LGF, Gonzaga-Silva LF, Nascimento NRF. Relaxant effect of a metal-based drug in human corpora cavernosa and its mechanism of action. Int J Impot Res 2015; 28:20-4. [PMID: 26510967 DOI: 10.1038/ijir.2015.27] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 07/10/2015] [Accepted: 09/22/2015] [Indexed: 11/09/2022]
Abstract
We studied the mechanisms involved in the human corpora cavernosa (HCC) relaxation induced by a new metal-based nitric oxide (NO) donor, the ruthenium complex cis-[Ru(bpy)2Imn(NO)](+3) (FOR0811). FOR0811 produced relaxation in phenylephrine (PE)-precontracted HCC with a maximal response that achieved 112.9 ± 10.6%. There was no difference between the maximal relaxation induced by FOR0811 when compared with sodium nitroprusside (SNP) (106.8 ± 7.3%), BAY41-2272 (107.6 ± 4.1%) or vardenafil (103.4 ± 3.8%), however, FOR0811 was less potent than SNP and vardenafil. L-N(G)-nitroarginine methyl ester (L-NAME), a NO synthase inhibitor, had no effect in the concentration-response curve elicited by FOR0811. 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a heme-site inhibitor of soluble guanylyl cyclase (sGC) was able to either block or reverse the relaxation induced by FOR0811. On the other hand, the relaxation induced by FOR0811 was not affected by glibenclamide, a blocker of ATP-sensitive potassium channels. FOR0811 (10 μM) was able to increase cyclic guanosine monophosphate (cGMP) levels in corpora cavernosa strips. FOR0811 completely relaxes HCC by a sGC-cGMP-dependent mechanism and can be a lead compound in the development of new stable NO donors.
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Affiliation(s)
- A S Leitão Junior
- Departamento de Cirurgia, Divisão de Urologia, Universidade Federal do Ceará, Fortaleza, Brazil
| | - R M Campos
- Physiology and Pharmacology, Instituto Superior de Ciências Biomédicas, Universidade Estadual do Ceará, Fortaleza, Brazil
| | - J B G Cerqueira
- Departamento de Cirurgia, Divisão de Urologia, Universidade Federal do Ceará, Fortaleza, Brazil
| | - M C Fonteles
- Departamento de Fisiologia e Farmacologia, Universidade Federal do Ceará, Fortaleza, Brazil
| | - C F Santos
- Physiology and Pharmacology, Instituto Superior de Ciências Biomédicas, Universidade Estadual do Ceará, Fortaleza, Brazil
| | - G de Nucci
- Faculdade de Ciências Médicas, Departamento de Farmacologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
| | - E H S Sousa
- Departamento de Química Orgânica e Inorgânica, Universidade Federal do Ceará, Fortaleza, Brazil
| | - L G F Lopes
- Departamento de Química Orgânica e Inorgânica, Universidade Federal do Ceará, Fortaleza, Brazil
| | - L F Gonzaga-Silva
- Departamento de Cirurgia, Divisão de Urologia, Universidade Federal do Ceará, Fortaleza, Brazil
| | - N R F Nascimento
- Physiology and Pharmacology, Instituto Superior de Ciências Biomédicas, Universidade Estadual do Ceará, Fortaleza, Brazil
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Dalaklioglu S, Ozbey G. Role of different types of potassium channels in the relaxation of corpus cavernosum induced by resveratrol. Pharmacogn Mag 2014; 10:47-52. [PMID: 24696545 PMCID: PMC3969658 DOI: 10.4103/0973-1296.126658] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Revised: 04/24/2013] [Accepted: 02/07/2014] [Indexed: 01/14/2023] Open
Abstract
Background: Resveratrol (RVT), one of the most commonly employed dietary polyphenol, is used in traditional Japanese and Chinese medicine for treatment of cardiovascular diseases. Recently, we have shown that RVT has a potent relaxant effect on rat corpus cavernosum via endothelium-dependent and -independent mechanisms. Objective: The present study addressed the question whether different types of potassium channels are involved in the endothelium-dependent and -independent mechanism of corpus cavernosum relaxation induced by RVT. Materials and Methods: Strips of corpus cavernosum from rats were mounted in an organ-bath system for isometric tension studies. Results: RVT (1-100 μmol/L) produced concentration-dependent relaxation responses in rat corpus cavernosum pre-contracted by phenylephrine. The non-selective potassium channels blocker tetraethylammonium chloride (TEA, 10 mmol/L), ATP-sensitive potassium (KATP) channels blocker glibenclamide (10 μmol/L), and inward rectifier potassium (Kir) channels inhibitor barium chloride (BaCl2, 30 μmol/L) caused a significant inhibition on the relaxation response to RVT, whereas voltage-dependent potassium channels inhibitor 4-aminopyridine (4-AP, 1 mmol/L), and large conductance calcium-activated potassium (BKCa) channels inhibitor iberiotoxin (IbTX, 0.1 μmol/L) did not significantly alter relaxant responses of corpus cavernosum strips to RVT. In addition, relaxant responses to RVT did not significantly inhibited by the combination of selective inhibitors of small and intermediate conductance BKCa channels (0.1 μmol/L charybdotoxin and 1 μmol/L apamin, respectively). Conclusion: These results demonstrated that endothelial small and intermediate conductance BKCa channels are not thought to be an important role in RVT-induced endothelium-dependent relaxation of corpus cavernosum. The endothelium-independent corpus cavernosum relaxation induced by RVT is seems to largely depend on Kir channels and KATP channels in corporal tissue.
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Affiliation(s)
- Selvinaz Dalaklioglu
- Department of Pharmacology, Akdeniz University, Medical Faculty, 07070, Antalya, Turkey
| | - G Ozbey
- Department of Pharmacology, Akdeniz University, Medical Faculty, 07070, Antalya, Turkey
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Lee JH, Chae MR, Park JK, Jeon JH, Lee SW. The effects of the combined use of a PDE5 inhibitor and medications for hypertension, lower urinary tract symptoms and dyslipidemia on corporal tissue tone. Int J Impot Res 2012; 24:221-7. [PMID: 22763627 DOI: 10.1038/ijir.2012.19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
ED is closely associated with its comorbidities (hypertension, dyslipidemia and lower urinary tract symptoms (LUTS)). Therefore, several drugs have been prescribed simultaneously with PDE5 inhibitors. If a specific medication for ED comorbidities has enhancing effects on PDE5 inhibitors, it offers alternative combination therapy in nonresponders to monotherapy with PDE5 inhibitors and allows clinicians to treat ED and its comorbidities simultaneously. To establish theoretical basis of choosing an appropriate medication for ED and concomitant disease, we examined the effects combining a PDE5 inhibitor with representative drugs for hypertension, dyslipidemia and LUTS on relaxing the corpus cavernosum of rabbits using the organ-bath technique. The effect of mirodenafil on relaxing phenylephrine-induced cavernosal contractions was significantly enhanced by the presence of 10(-4) M losartan, 10(-6) M nifedipine, 10(-6) M amlodipine, 10(-7) M doxazosin and 10(-9) M tamsulosin (P<0.05). The maximum relaxation effects were 47.2±3.8%, 57.6±2.6%, 64.0±3.7%, 76.1±5.7% and 71.7±5.4%, respectively. Enalapril and simvastatin had no enhancing effects. The relaxation induced by sodium nitroprusside alone (39.0±4.0%) was significantly enhanced in the presence of the 10(-4) M losartan (66.0±6.0%, P<0.05). Tetraethylammonium (1 mM) significantly inhibited the enhancement effects of tamsulosin and doxazosin on mirodenafil-induced relaxation (doxazosin: 76.1±5.7% vs 45.3±2.3%; tamsulosin: 71.7±5.4% vs 48.1±3.5%). On the basis of these findings, losartan seemed to induce synergistic effects through an interaction with nitric oxide. In addition, K(+) channel activation could be one of the mechanisms for the synergistic effect of combining mirodenafil with doxazosin or tamsulosin. We believe that the combination of a PDE5 inhibitor with losartan, nifedipine, amlodipine, doxazosin or tamsulosin could be a pharmacologic strategy for simultaneously treating ED and its comorbidities and increasing response rates to PDE5 inhibitors.
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Affiliation(s)
- J H Lee
- Genitourinary Disease Oriented Translational Research, Seoul, Korea
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Andersson KE. Mechanisms of penile erection and basis for pharmacological treatment of erectile dysfunction. Pharmacol Rev 2011; 63:811-59. [PMID: 21880989 DOI: 10.1124/pr.111.004515] [Citation(s) in RCA: 232] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Erection is basically a spinal reflex that can be initiated by recruitment of penile afferents, both autonomic and somatic, and supraspinal influences from visual, olfactory, and imaginary stimuli. Several central transmitters are involved in the erectile control. Dopamine, acetylcholine, nitric oxide (NO), and peptides, such as oxytocin and adrenocorticotropin/α-melanocyte-stimulating hormone, have a facilitatory role, whereas serotonin may be either facilitatory or inhibitory, and enkephalins are inhibitory. The balance between contractant and relaxant factors controls the degree of contraction of the smooth muscle of the corpora cavernosa (CC) and determines the functional state of the penis. Noradrenaline contracts both CC and penile vessels via stimulation of α₁-adrenoceptors. Neurogenic NO is considered the most important factor for relaxation of penile vessels and CC. The role of other mediators, released from nerves or endothelium, has not been definitely established. Erectile dysfunction (ED), defined as the "inability to achieve or maintain an erection adequate for sexual satisfaction," may have multiple causes and can be classified as psychogenic, vasculogenic or organic, neurologic, and endocrinologic. Many patients with ED respond well to the pharmacological treatments that are currently available, but there are still groups of patients in whom the response is unsatisfactory. The drugs used are able to substitute, partially or completely, the malfunctioning endogenous mechanisms that control penile erection. Most drugs have a direct action on penile tissue facilitating penile smooth muscle relaxation, including oral phosphodiesterase inhibitors and intracavernosal injections of prostaglandin E₁. Irrespective of the underlying cause, these drugs are effective in the majority of cases. Drugs with a central site of action have so far not been very successful. There is a need for therapeutic alternatives. This requires identification of new therapeutic targets and design of new approaches. Research in the field is expanding, and several promising new targets for future drugs have been identified.
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Affiliation(s)
- K-E Andersson
- Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Medical Center Boulevard, Winston Salem, NC 27157, USA.
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Ahn SW, Kim SH, Kim JH, Choi S, Yeum CH, Wie HW, Sun JM, So I, Jun JY. Phentolamine inhibits the pacemaker activity of mouse interstitial cells of Cajal by activating ATP-sensitive K+ channels. Arch Pharm Res 2010; 33:479-89. [DOI: 10.1007/s12272-010-0319-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 01/07/2010] [Accepted: 01/18/2010] [Indexed: 01/18/2023]
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Yohimbine relaxes the human corpus cavernosum through a non-adrenergic mechanism involving the activation of K+ATP-dependent channels. Int J Impot Res 2009; 21:356-61. [PMID: 19759544 DOI: 10.1038/ijir.2009.41] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The mechanism by which yohimbine relaxes the human corpus cavernosum remains unclear. Using the human corpus cavernosum strips immersed in isometric baths containing Krebs-Henseleit solution, this study investigates the effect of yohimbine on the relaxation of the human corpus cavernosum through nitrergic pathways involving the activation of ATP-dependent potassium channels (K(ATP)). The maximal relaxation induced by yohimbine in the human corpus cavernosum strips pre-contracted with phenylephrine was 100+/-0% and only 30.5+/-5.0% when they were pre-contracted with 60-mM potassium (K(+)) solution. The maximal relaxation induced by yohimbine in phenylephrine pre-contracted tissues was significantly inhibited by tetrodotoxin, 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) or 7-nitroindazole (43.6, 36.1 and 42.6%, respectively). Neither the combination charybdotoxin-apamin nor tetraethylammonium altered the response of the human corpora cavernosa strips to yohimbine. Nevertheless, glibenclamide decreased the maximum relaxant response to yohimbine by 29.8% (P<0.05; n=12). The results suggest that yohimbine relaxes the human corpus cavernosum by a non-adrenergic, non-cholinergic mechanism, probably activating the nitrergic-soluble guanylate cyclase (NO-sGc) pathway and K(ATP).
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Testosterone Might Cause Relaxation of Human Corpus Cavernosum by Potassium Channel Opening Action. Urology 2009; 74:229-32. [DOI: 10.1016/j.urology.2008.12.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Revised: 11/28/2008] [Accepted: 12/06/2008] [Indexed: 11/17/2022]
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Oger S, Behr-Roussel D, Gorny D, Charles Tremeaux J, Combes M, Alexandre L, Giuliano F. Combination of alfuzosin and tadalafil exerts in vitro an additive relaxant effect on human corpus cavernosum. J Sex Med 2008; 5:935-945. [PMID: 18221277 DOI: 10.1111/j.1743-6109.2007.00754.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
INTRODUCTION Phosphodiesterase type 5 (PDE5) inhibitors, such as tadalafil, are a first-line treatment for erectile dysfunction (ED). Nevertheless, some patients do not respond to this treatment. Clinical data suggest that the addition of alpha1-adrenoceptor blocker, such as alfuzosin, commonly prescribed for lower urinary tract symptoms suggestive of benign prostatic hyperplasia, may be of benefit. Aim. Evaluation of the effect of alfuzosin, tadalafil or the combination of both on human corpus cavernosum. METHODS Human cavernosal tissues were obtained from 10 patients undergoing penile surgery. Strips contractility was studied in organ baths. Concentration-response curves to tadalafil were generated on norepinephrine (NE, 1-10 microM)-precontracted strips in the presence of alfuzosin or vehicle. Frequency-response curves (FRC) to electrical field stimulation (EFS, 0-64 Hz, 3 ms, 10 seconds, 300 mA) were generated in the presence of vehicle, alfuzosin, tadalafil, or both drugs combined. EFS (20 Hz, 1 ms, 10 seconds, 300 mM)-induced nitrergic relaxation on NE-precontracted strips was studied in the presence of vehicle, alfuzosin, tadalafil, or both drugs combined. MAIN OUTCOME MEASURES Functional measurement of cavernosal smooth muscle relaxation in the presence of tadalafil and alfuzosin. RESULTS The relaxation induced by tadalafil (10(-10) to 10(-5) M) on precontracted strips was enhanced by alfuzosin at both 10(-8) and 10(-7) M. The combination of alfuzosin (3.10(-8) M) and tadalafil (10(-7) M) was more efficient to inhibit FRC-induced contractions than each compound alone. The combination of tadalafil (10(-6) M) and alfuzosin (10(-8) M) increased the relaxation induced by EFS and its effect was greater than tadalafil alone. In addition, the combination of tadalafil (10(-6) M) and alfuzosin (10(-7) M) prolonged EFS-induced relaxation to a greater extent than each compound alone. CONCLUSIONS In vitro, the combination of alfuzosin and tadalafil is more efficient than each compound alone to relax adrenergic tone or to enhance nitrergic relaxation of the human corpus cavernosum. Such a combination deserves further investigation in placebo-controlled studies to evaluate its benefit in ED patients who are not sufficiently improved by PDE5 inhibitors.
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Affiliation(s)
| | | | | | | | | | | | - François Giuliano
- Raymond Poincaré Hospital-Department of Physical Medicine and Rehabilitation, Garches, France.
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Hong SS, Bavadekar SA, Lee SI, Patil PN, Lalchandani SG, Feller DR, Miller DD. Bioisosteric phentolamine analogs as potent α-adrenergic antagonists. Bioorg Med Chem Lett 2005; 15:4691-5. [PMID: 16153828 DOI: 10.1016/j.bmcl.2005.07.083] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2005] [Revised: 07/28/2005] [Accepted: 07/28/2005] [Indexed: 10/25/2022]
Abstract
The synthesis and biological evaluation of a new series of bioisosteric phentolamine analogs are described. Replacement of the carbon next to the imidazoline ring of phentolamine with a nitrogen atom provides compounds (2, 3) that are about 1.6 times and 4.1 times more potent functionally than phentolamine on rat alpha1-adrenergic receptors, respectively. In receptor binding assays, the affinities of phentolamine and its bioisosteric analogs were determined on the human embryonic kidney (HEK) and Chinese Hamster ovary (CHO) cell lines expressing the human alpha1- and alpha2-AR subtypes, respectively. Analogs 2 and 3, both, displayed higher binding affinities at the alpha2- versus the alpha1-ARs, affinities being the least at the alpha1B-AR. Binding affinities of the methoxy ether analog 2 were greater than those of the phenolic analog 3 at all six alpha-AR subtypes. One of the nitrogen atoms in the imidazoline ring of phentolamine was replaced with an oxygen atom to give compounds 4 and 5, resulting in a 2-substituted oxazoline ring. The low functional antagonist activity on rat aorta, and binding potencies of these two compounds on human alpha1A- and alpha2A-AR subtypes indicate that a basic functional group is important for optimum binding to the alpha1- and alpha2A-adrenergic receptors.
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Affiliation(s)
- Seoung-Soo Hong
- Department of Manufacturing Pharmacy, College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 360-763, Republic of Korea.
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