1
|
Bérard A, Levin M, Sadler T, Healy D. Selective Serotonin Reuptake Inhibitor Use During Pregnancy and Major Malformations: The Importance of Serotonin for Embryonic Development and the Effect of Serotonin Inhibition on the Occurrence of Malformations. Bioelectricity 2019; 1:18-29. [PMID: 34471805 DOI: 10.1089/bioe.2018.0003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Bioelectric signaling is transduced by neurotransmitter pathways in many cell types. One of the key mediators of bioelectric control mechanisms is serotonin, and its transporter SERT, which is targeted by a broad class of blocker drugs (selective serotonin reuptake inhibitors [SSRIs]). Studies showing an increased risk of multiple malformations associated with gestational use of SSRI have been accumulating but debate remains on whether SSRI as a class has the potential to generate these malformations. This review highlights the importance of serotonin for embryonic development; the effect of serotonin inhibition during early pregnancy on the occurrence of multiple diverse malformations that have been shown to occur in human pregnancies; that the risks outweigh the benefits of SSRI use during gestation in populations of mild to moderately depressed pregnant women, which encompass the majority of pregnant depressed women; and that the malformations seen in human pregnancies constitute a pattern of malformations consistent with the known mechanisms of action of SSRIs. We present at least three mechanisms by which SSRI can affect development. These studies highlight the relevance of basic bioelectric and neurotransmitter mechanism for biomedicine.
Collapse
Affiliation(s)
- Anick Bérard
- Faculty of Pharmacy, University of Montreal; Research Center, CHU Sainte-Justine, Montreal, Quebec, Canada
| | - Michael Levin
- Allen Discovery Center at Tufts University, Department of Biology, Medford, Massachusetts
| | - Thomas Sadler
- Department of Pediatrics, School of Medicine, University of Utah, Salt Lake City, Utah
| | - David Healy
- Department of Psychiatry, Hergest Unit, Bangor, United Kingdom
| |
Collapse
|
2
|
Luo Q, Wang X, Liu R, Qiao H, Wang P, Jiang C, Zhang Q, Cao Y, Yu H, Qu L. alpha1A-adrenoceptor is involved in norepinephrine-induced proliferation of pulmonary artery smooth muscle cells via CaMKII signaling. J Cell Biochem 2018; 120:9345-9355. [PMID: 30520144 DOI: 10.1002/jcb.28210] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 11/15/2018] [Indexed: 12/13/2022]
Abstract
Pulmonary arterial hypertension (PAH) is a progressive disease of the pulmonary vasculature characterized by excessive proliferation of pulmonary artery smooth muscle cells (PASMCs). Some studies have demonstrated the sympathetic nervous system is activated in PAH and norepinephrine (NE) released is closely linked with its activation. However, the subtypes of adrenoreceptor (AR) and the downstream molecular cascades which are involved in the proliferation of PASMCs are still unclear. In this study, adult male Wistar rats were exposed to chronic hypoxia and PASMCs were cultured in hypoxic condition. Significant upregulation of α1A -AR was identified by Western blot analysis or immunofluorescence in all of the pulmonary arteries, lung tissues, and cell hypoxic models. Western blot analysis, flow cytometry, and immunofluorescence were applied to detect the roles of α1A -AR in NE mediated proliferation of PASMCs. We revealed 5-methylurapidil (5-MU) reversed NE-induced upregulation of PCNA, CyclinA and CyclinE, more cells from G0 /G1 phase to G2 /M+S phase, enhancement of the microtubule formation. In addition, we found calcium/calmodulin(CaM)-dependent protein kinase type II (CaMKII) pathway was involved in α1A -AR-mediated cell proliferation. [Ca2+ ]i measurements showed that an increase of [Ca2+ ]i caused by NE or/and hypoxia could be blocked by 5-MU in PASMCs. Western blot analysis results demonstrated the augmentation of CaMKII phosphorylation level was caused by hypoxia or NE in pulmonary arteries, lung tissues, and PASMCs. KN62 attenuated NE-induced proliferation of PASMCs under normoxia and hypoxia. In conclusion, those results suggested NE which stimulated α1A -AR-mediated the proliferation of PASMCs, which may be via the CaMKII pathway, and it could be used as a novel treatment strategy in PAH.
Collapse
Affiliation(s)
- Qian Luo
- Department of Physiology, College of Basic Medical Sciences, Harbin Medical University-Daqing, Daqing, China
| | - Xiaoyan Wang
- Department of Physiology, College of Basic Medical Sciences, Harbin Medical University-Daqing, Daqing, China
| | - Ruxia Liu
- Department of Physiology, College of Basic Medical Sciences, Harbin Medical University-Daqing, Daqing, China
| | - Hui Qiao
- Department of Physiology, College of Basic Medical Sciences, Harbin Medical University-Daqing, Daqing, China.,Department of Gastroenterology, Daqing Oilfield General Hospital, Daqing, China
| | - Peng Wang
- Department of Physiology, College of Basic Medical Sciences, Harbin Medical University-Daqing, Daqing, China
| | - Chao Jiang
- Department of Physiology, College of Basic Medical Sciences, Harbin Medical University-Daqing, Daqing, China
| | - Qianlong Zhang
- Department of Physiology, College of Basic Medical Sciences, Harbin Medical University-Daqing, Daqing, China
| | - Yonggang Cao
- Department of Pharmacology, College of Basic Medical Sciences, Harbin Medical University-Daqing, Daqing, China
| | - Hang Yu
- Department of Physiology, College of Basic Medical Sciences, Harbin Medical University-Daqing, Daqing, China
| | - Lihui Qu
- Department of Physiology, College of Basic Medical Sciences, Harbin Medical University-Daqing, Daqing, China
| |
Collapse
|
3
|
Vasodilator effects and putative guanylyl cyclase stimulation by 2-nitro-1-phenylethanone and 2-nitro-2-phenyl-propane-1,3-diol on rat aorta. Eur J Pharmacol 2018; 830:105-114. [DOI: 10.1016/j.ejphar.2018.04.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 04/19/2018] [Accepted: 04/25/2018] [Indexed: 12/15/2022]
|
4
|
de Brito TS, Batista-Lima FJ, Gadelha KKL, da Fonseca-Magalhães PA, Lahlou S, Magalhães PJC. Vasorelaxant effects of 2-nitro-1-phenyl-1-propanol in rat aorta. Clin Exp Pharmacol Physiol 2017; 43:1054-1061. [PMID: 27437904 DOI: 10.1111/1440-1681.12625] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 07/11/2016] [Accepted: 07/14/2016] [Indexed: 11/29/2022]
Abstract
2-Nitro-1-phenyl-1-propanol (NPP) is a nitro alcohol that is known as an intermediate in the synthesis of sympathomimetic agents, such as norephedrine. The present study investigated the vasoactive effects of NPP on rat aorta. In endothelium-intact aortic rings, NPP fully relaxed contractions that were induced by phenylephrine, KCl, and U-46619. The relaxant effects of NPP on phenylephrine-elicited contractions remained unaffected by NG-nitro-l-arginine methyl ester (l-NAME), indomethacin, propranolol, tetraethylammonium, 4-aminopyridine, and glibenclamide. Conversely, pretreatment with 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), cis-N-(2-phenylcyclopentyl)-azacyclotridec-1-en-2-amine hydrochloride (MDL-12,330A), and N-[2-(P-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride (H-89) reduced the ability of NPP to relax contractions that were elicited by phenylephrine. NPP inhibited the vasoconstrictor response that was induced by Ca2+ in aortic rings that were stimulated by pharmacomechanical or electromechanical coupling with phenylephrine and 60 mmol/L KCl, respectively, and after the depletion of intracellular Ca2+ stores. Such effects of NPP were significantly reversed by pretreatment with the guanylyl cyclase inhibitor ODQ and weakly influenced by the adenylyl cyclase inhibitor MDL-12,330A. In Ca2+ -free medium, NPP inhibited transient contractions that were induced by phenylephrine but not caffeine. In homogenates of aortic rings, NPP increased cyclic guanosine 3',5'-monophosphate (cGMP) and cyclic adenosine 3'-5'-monophosphate levels, but this effect was statistically significant only for cGMP. In conclusion, in contrast to the vasoconstrictor amine norephedrine, NPP is a vasodilator in rat aorta, and its relaxant effects are likely attributable to cGMP production.
Collapse
Affiliation(s)
- Teresinha Silva de Brito
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Brazil
| | - Francisco José Batista-Lima
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Brazil
| | - Kalinne Kelly Lima Gadelha
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Brazil
| | | | - Saad Lahlou
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Brazil
| | | |
Collapse
|
5
|
Chen YC, Yuan TY, Zhang HF, Wang DS, Niu ZR, Li L, Fang LH, Du GH. Fasudil evokes vasodilatation of rat mesenteric vascular bed via Ca(2+) channels and Rho/ROCK pathway. Eur J Pharmacol 2016; 788:226-233. [PMID: 27346833 DOI: 10.1016/j.ejphar.2016.06.041] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 06/21/2016] [Accepted: 06/22/2016] [Indexed: 01/24/2023]
Abstract
As a Rho kinase (ROCK) inhibitor, fasudil has been used in clinical trials of several cardiovascular diseases. This study was to investigate the vasorelaxant effect of fasudil on resistance arterial rings including mesenteric, renal, ventral tail and basilar artery. We also examined the potential mechanisms of its vasodilatory action using mesenteric artery rings. A DMT multiwire myograph system was used to test the tension of isolated small arteries. K(+) channel blockers, NO-cGMP pathway blockers and Ca(2+)-free physiological salt solution (PSS) were employed to verify the underlying mechanisms. Fasudil (10(-7)-10(-4)M) relaxed four types of small artery rings pre-contracted by 60mmol/l KCl (pEC50: 6.01±0.09, 5.47±0.03, 5.54±0.04, and 5.72±0.10 for mesenteric, renal, ventral tail and basilar artery rings, respectively). Pre-incubation with fasudil (1, 3, or 10μmol/l) attenuated KCl (10-60mmol/l) and angiotensin II (Ang II; 1μmol/l)-induced vasoconstriction in mesenteric artery rings. Fasudil at the concentration of 10(-6)mol/l showed different relaxant potency in endothelium intact (pEC50:6.01±0.09) or denued (5.75±0.06) mesenteric artery. The influx and release of Ca(2+) were inhibited by fasudil. In addition, fasudil could block the increased phosphorylation level of myosin light chain (MLC) and myosin-binding subunit of myosin phosphatase (MYPT1) induced by Ang II. However, pretreatment with various K(+) channel blockers did not affect the relaxant effects of fasudil remarkably. The present results demonstrate that fasudil has a vasorelaxant effect on isolated rat resistance arteries, including mesenteric, renal, ventral tail and basilar artery, and may exert its action through the endothelium, Ca(2+) channels, and the Rho/ROCK pathway.
Collapse
Affiliation(s)
- Yu-Cai Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, China
| | - Tian-Yi Yuan
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, China
| | - Hui-Fang Zhang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, China
| | - Dan-Shu Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, China
| | - Zi-Ran Niu
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, China
| | - Li Li
- Beijing Key Laboratory of Drug Targets Identification and Drug Screening, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Lian-Hua Fang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, China.
| | - Guan-Hua Du
- Beijing Key Laboratory of Drug Targets Identification and Drug Screening, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
| |
Collapse
|
6
|
Lee HM, Hahn SJ, Choi BH. Blockade of Kv1.5 channels by the antidepressant drug sertraline. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2016; 20:193-200. [PMID: 26937216 PMCID: PMC4770110 DOI: 10.4196/kjpp.2016.20.2.193] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 02/03/2016] [Accepted: 02/12/2016] [Indexed: 11/15/2022]
Abstract
Sertraline, a selective serotonin reuptake inhibitor (SSRI), has been reported to lead to cardiac toxicity even at therapeutic doses including sudden cardiac death and ventricular arrhythmia. And in a SSRI-independent manner, sertraline has been known to inhibit various voltage-dependent channels, which play an important role in regulation of cardiovascular system. In the present study, we investigated the action of sertraline on Kv1.5, which is one of cardiac ion channels. The eff ect of sertraline on the cloned neuronal rat Kv1.5 channels stably expressed in Chinese hamster ovary cells was investigated using the whole-cell patch-clamp technique. Sertraline reduced Kv1.5 whole-cell currents in a reversible concentration-dependent manner, with an IC 50 value and a Hill coefficient of 0.71 µM and 1.29, respectively. Sertraline accelerated the decay rate of inactivation of Kv1.5 currents without modifying the kinetics of current activation. The inhibition increased steeply between -20 and 0 mV, which corresponded with the voltage range for channel opening. In the voltage range positive to +10 mV, inhibition displayed a weak voltage dependence, consistent with an electrical distance δ of 0.16. Sertraline slowed the deactivation time course, resulting in a tail crossover phenomenon when the tail currents, recorded in the presence and absence of sertraline, were superimposed. Inhibition of Kv1.5 by sertraline was use-dependent. The present results suggest that sertraline acts on Kv1.5 currents as an open-channel blocker.
Collapse
Affiliation(s)
- Hyang Mi Lee
- Department of Pharmacology, Institute for Medical Sciences, Chonbuk National University Medical School, Jeonju 54097, Korea
| | - Sang June Hahn
- Department of Physiology, Medical Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Bok Hee Choi
- Department of Pharmacology, Institute for Medical Sciences, Chonbuk National University Medical School, Jeonju 54097, Korea
| |
Collapse
|
7
|
Vasodilatory effect of a novel Rho-kinase inhibitor, DL0805-2, on the rat mesenteric artery and its potential mechanisms. Cardiovasc Drugs Ther 2015; 28:415-24. [PMID: 25086815 DOI: 10.1007/s10557-014-6544-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE In the present study, we investigated the vasodilatory effect of a novel scaffold Rho-kinase inhibitor, DL0805-2, on isolated rat arterial rings including mesenteric, ventral tail, and renal arteries. We also examined the potential mechanisms of its vasodilatory action using mesenteric artery rings. METHODS A DMT multiwire myograph system was used to test the tension of isolated small arteries. Several drugs were employed to verify the underlying mechanisms. RESULTS DL0805-2 (10(-7)-10(-4) M) inhibited KCl (60 mM)-induced vasoconstriction in three types of small artery rings (pEC50: 5.84 ± 0.03, 5.39 ± 0.03, and 5.67 ± 0.02 for mesenteric, renal, and ventral tail artery rings, respectively). Pre-incubation with DL0805-2 (1, 3, or 10 μM) attenuated KCl (10-60 mM) and angiotensin II (AngII; 10(-6) M)-induced vasoconstriction in mesenteric artery rings. The relaxant effect on the rat mesenteric artery was partially endothelium-dependent (pEC50: 6.02 ± 0.05 for endothelium-intact and 5.72 ± 0.06 for endothelium-denuded). The influx and release of Ca(2+) were inhibited by DL0805-2. In addition, the increased phosphorylation levels of myosin light chain (MLC) and myosin-binding subunit of myosin phosphatase (MYPT1) induced by AngII were blocked by DL0805-2. However, DL0805-2 had little effect on K(+) channels. CONCLUSIONS The present results demonstrate that DL0805-2 has a vasorelaxant effect on isolated rat small arteries and may exert its action through the endothelium, Ca(2+) channels, and the Rho/ROCK pathway.
Collapse
|
8
|
Gai XY, Wei YH, Zhang W, Wuren TN, Wang YP, Li ZQ, Liu S, Ma L, Lu DX, Zhou Y, Ge RL. Echinacoside induces rat pulmonary artery vasorelaxation by opening the NO-cGMP-PKG-BKCa channels and reducing intracellular Ca2+ levels. Acta Pharmacol Sin 2015; 36:587-96. [PMID: 25864652 DOI: 10.1038/aps.2014.126] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 10/14/2014] [Indexed: 01/18/2023] Open
Abstract
AIM Sustained pulmonary vasoconstriction as experienced at high altitude can lead to pulmonary hypertension (PH). The main purpose of this study is to investigate the vasorelaxant effect of echinacoside (ECH), a phenylethanoid glycoside from the Tibetan herb Lagotis brevituba Maxim and Cistanche tubulosa, on the pulmonary artery and its potential mechanism. METHODS Pulmonary arterial rings obtained from male Wistar rats were suspended in organ chambers filled with Krebs-Henseleit solution, and isometric tension was measured using a force transducer. Intracellular Ca(2+) levels were measured in cultured rat pulmonary arterial smooth muscle cells (PASMCs) using Fluo 4-AM. RESULTS ECH (30-300 μmol/L) relaxed rat pulmonary arteries precontracted by noradrenaline (NE) in a concentration-dependent manner, and this effect could be observed in both intact endothelium and endothelium-denuded rings, but with a significantly lower maximum response and a higher EC50 in endothelium-denuded rings. This effect was significantly blocked by L-NAME, TEA, and BaCl2. However, IMT, 4-AP, and Gli did not inhibit ECH-induced relaxation. Under extracellular Ca(2+)-free conditions, the maximum contraction was reduced to 24.54%±2.97% and 10.60%±2.07% in rings treated with 100 and 300 μmol/L of ECH, respectively. Under extracellular calcium influx conditions, the maximum contraction was reduced to 112.42%±7.30%, 100.29%±8.66%, and 74.74%±4.95% in rings treated with 30, 100, and 300 μmol/L of ECH, respectively. After cells were loaded with Fluo 4-AM, the mean fluorescence intensity was lower in cells treated with ECH (100 μmol/L) than with NE. CONCLUSION ECH suppresses NE-induced contraction of rat pulmonary artery via reducing intracellular Ca(2+) levels, and induces its relaxation through the NO-cGMP pathway and opening of K(+) channels (BKCa and KIR).
Collapse
|
9
|
Vargas-Tendero P, Rodríguez-Gómez I, Wangensteen R, Arcas R, Quintana M, Vargas F. New method for isolation of both kidneys for studies of vascular reactivity in rats. Exp Biol Med (Maywood) 2013; 237:1457-61. [PMID: 23354404 DOI: 10.1258/ebm.2012.012231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The isolated perfused rat kidney technique is one of the most widely used methods in renal research. It has proven useful to investigate biochemical, physiological, pharmacological and pathophysiological aspects of renal function, allowing variables to be changed in a controlled manner and eliminating systemic influences. This study was designed to test a new surgical procedure to isolate both kidneys for their utilization in this technique, mainly as a vascular preparation. The viability of the resulting preparations was compared with those obtained by the classical method, analyzing the responsiveness to the vasoconstrictor phenylephrine and to the endothelium-dependent vasodilator acetylcholine. Vascular reactivity was evaluated under normal conditions and in endothelium-denuded preparations. The dose response curves to phenylephrine and to acetylcholine were similar in the three experimental groups, regardless of the procedure used for kidney isolation, in both endothelium-intact and endothelium-denuded preparations. We give a step-by-step description of the isolation method and key points for the success of the technique. In conclusion, the surgical procedure proposed in this paper reduces the number of animals required by half and hence reduces the cost of the experiments. This novel procedure is of special interest for acute experiments to test new vasoactive drugs and for analysis of the action mechanisms of these drugs. It could also be used in chronic studies or in genetically modified animals when different experimental protocols are performed on the left and right kidneys and to improve the accuracy of the results by analyzing cases in duplicate.
Collapse
Affiliation(s)
- Pablo Vargas-Tendero
- Departamento de Fisiología, Facultad de Medicina, Universidad de Granada, E-18012 Granada
| | | | | | | | | | | |
Collapse
|
10
|
Interaminense LDFL, dos Ramos-Alves FE, de Siqueira RJB, Xavier FE, Duarte GP, Magalhães PJC, Maia JGS, Sousa PJDC, Lahlou S. Vasorelaxant effects of 1-nitro-2-phenylethane, the main constituent of the essential oil of Aniba canelilla, in superior mesenteric arteries from spontaneously hypertensive rats. Eur J Pharm Sci 2013; 48:709-16. [PMID: 23313621 DOI: 10.1016/j.ejps.2012.12.033] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 12/25/2012] [Accepted: 12/30/2012] [Indexed: 10/27/2022]
Abstract
The present study investigated the mechanisms underlying the vasorelaxant effects of the essential oil of Aniba canelilla (EOAC) and its main constituent 1-nitro-2-phenylethane (NP) in isolated superior mesenteric artery from spontaneously hypertensive rats (SHRs). At 0.1-1000 μg/mL, EOAC and NP relaxed SMA preparations pre-contracted with 75 mMKCl with IC(50) (geometric mean [95% confidence interval]) values of 294.19 [158.20-94.64] and 501.27 [378.60-624.00] μg/mL, respectively); or with phenylephrine (PHE) (IC(50)s=11.07 [6.40-15.68] and 7.91 [4.08-11.74) μg/mL, respectively). All these effects were reversible and remained unaltered by vascular endothelium removal. In preparations maintained under Ca(2+)-free conditions, EOAC and NP (both at 600 μg/mL) reduced the PHE-, but not the caffeine-induced contraction. In Ca(2+)-free and high K(+) (75 mM) medium, the contractions produced by CaCl(2) or BaCl(2) were reduced or even abolished by EOAC and NP at 100 and 600 μg/mL, respectively. EOAC and NP (both at 10-1000 μg/mL) also relaxed the contraction evoked by phorbol dibutyrate (IC(50)=52.66 [10.82-94.64] and 39.13 [31.55-46.72] μg/mL, respectively). It is concluded that NP has a myogenic endothelium-independent vasorelaxant effects and appears to be the active principle of the EOAC. Vasorelaxant effect induced by both EOAC and NP is preferential to receptor-activated pathways and it appears to occur intracellularly more than a superficial action restricted to the membrane environment such as a simple blocking activity on a given receptor or ion channel.
Collapse
|