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Zigmantaitė V, Jonušaitė E, Grigalevičiūtė R, Kučinskas A, Treinys R, Navalinskas A, Žvikas V, Jakštas V, Pudžiuvelytė L, Bernatonienė J, Mačianskienė R, Jurevičius J. Evaluation of the Cardiac Electrophysiological and Haemodynamic Effects of Elsholtzia ciliata Essential Oil on Swine. Pharmaceuticals (Basel) 2022; 15:ph15080982. [PMID: 36015131 PMCID: PMC9414655 DOI: 10.3390/ph15080982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 08/01/2022] [Accepted: 08/06/2022] [Indexed: 11/16/2022] Open
Abstract
The demand for the development of novel medicines with few side effects and no proarrhythmic properties is increasing. Extensive research on herbal extracts has been conducted with the expectation that the compounds will exert precise effects without harmful side effects. Elsholtzia ciliata (Thunb.) Hyl. essential oil (EO) possesses antiarrhythmic properties similar to those of class 1B antiarrhythmics, such as prolonging myocardial activation of the QRS complex and shortening the QT interval. In this study, we determined the kinetic profile of EO phytocompounds and the effects of EO on heart electrical activity and arterial blood pressure. For this study, we chose to use local breed pigs that were anaesthetized. The effects of an intravenous bolus of EO on ECG parameters, arterial blood pressure, heart rate variability, and blood levels of haematological and biochemical parameters were registered and evaluated. Following an intravenous injection of a bolus, EO exerted a vasodilatory effect, resulting in significant reductions in arterial blood pressure. EO also increased the heart rate and altered ECG parameters. The bolus of EO prolonged the QRS complex, shortened the QT interval, and nonmonotonically altered the PQ interval. After the administration of a bolus of EO, the activity of the autonomic nervous system was altered. This study confirms that EO possesses similar properties to class 1B antiarrhythmics and exerts a hypotensive effect; it reduces arterial blood pressure possibly by modulating peripheral vascular resistance.
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Affiliation(s)
- Vilma Zigmantaitė
- Biological Research Center, Lithuanian University of Health Sciences, Tilžės St. 18/7, LT47181 Kaunas, Lithuania
- Correspondence: ; Tel.: +370-675-36043
| | - Eglė Jonušaitė
- Biological Research Center, Lithuanian University of Health Sciences, Tilžės St. 18/7, LT47181 Kaunas, Lithuania
| | - Ramunė Grigalevičiūtė
- Biological Research Center, Lithuanian University of Health Sciences, Tilžės St. 18/7, LT47181 Kaunas, Lithuania
| | - Audrius Kučinskas
- Biological Research Center, Lithuanian University of Health Sciences, Tilžės St. 18/7, LT47181 Kaunas, Lithuania
| | - Rimantas Treinys
- Laboratory of Membrane Biophysics, Institute of Cardiology, Lithuanian University of Health Sciences, Sukilėlių Ave. 15, LT50162 Kaunas, Lithuania
| | - Antanas Navalinskas
- Laboratory of Membrane Biophysics, Institute of Cardiology, Lithuanian University of Health Sciences, Sukilėlių Ave. 15, LT50162 Kaunas, Lithuania
| | - Vaidotas Žvikas
- Institute of Pharmaceutical Technologies, Faculty of Pharmacy, Lithuanian University of Health Sciences, Sukilėlių Ave. 13, LT50162 Kaunas, Lithuania
| | - Valdas Jakštas
- Institute of Pharmaceutical Technologies, Faculty of Pharmacy, Lithuanian University of Health Sciences, Sukilėlių Ave. 13, LT50162 Kaunas, Lithuania
- Laboratory of Biopharmaceutical Research, Institute of Pharmaceutical Technologies, Faculty of Pharmacy, Medical Academy, Lithuanian University of Health Sciences, Sukilėlių Ave. 13, LT50162 Kaunas, Lithuania
| | - Lauryna Pudžiuvelytė
- Institute of Pharmaceutical Technologies, Faculty of Pharmacy, Lithuanian University of Health Sciences, Sukilėlių Ave. 13, LT50162 Kaunas, Lithuania
- Department of Drug Technology and Social Pharmacy, Medical Academy, Lithuanian University of Health Sciences, Sukilėlių Ave. 13, LT50162 Kaunas, Lithuania
| | - Jurga Bernatonienė
- Institute of Pharmaceutical Technologies, Faculty of Pharmacy, Lithuanian University of Health Sciences, Sukilėlių Ave. 13, LT50162 Kaunas, Lithuania
- Department of Drug Technology and Social Pharmacy, Medical Academy, Lithuanian University of Health Sciences, Sukilėlių Ave. 13, LT50162 Kaunas, Lithuania
| | - Regina Mačianskienė
- Laboratory of Membrane Biophysics, Institute of Cardiology, Lithuanian University of Health Sciences, Sukilėlių Ave. 15, LT50162 Kaunas, Lithuania
| | - Jonas Jurevičius
- Laboratory of Membrane Biophysics, Institute of Cardiology, Lithuanian University of Health Sciences, Sukilėlių Ave. 15, LT50162 Kaunas, Lithuania
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Sadraei H, Ghasemi M, Saranji S. Evaluation of spasmolytic effects of naringenin on ileum contraction and intestinal charcoal meal transit: Involvement of ATP-sensitive K+ channels. JOURNAL OF HERBMED PHARMACOLOGY 2022. [DOI: 10.34172/jhp.2022.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Introduction: Naringenin is a flavonoid constituent of many herbal plants, including citreous fruits. Biological studies have suggested various therapeutic effects for naringenin, including protective effects on gastrointestinal (GI) motility. The present study was performed to investigate the involvement of ATP-sensitive K+ channels on the effect of naringenin in rat ileum motility. Methods: Ileum contractions were induced by either KCl or acetylcholine (ACh) in vitro. Inhibitory concentration-response curves were constructed for naringenin and diazoxide after exposure of rat isolated ileum to KCl (20mM) or ACh (500nM). The relaxant effects of naringenin and diazoxide were also examined in the presence of glibenclamide. Furthermore, oral effects of diazoxide (25 mg/kg) and naringenin (25, 50 mg/kg) were also assessed on the intestinal charcoal meal transit in mice (n=10) in the absence and presence of glibenclamide (50 mg/kg). Results: Diazoxide and naringenin in a concentration-dependent manner inhibited ileum contractions induced by low bath concentration of KCl (20mM). However, both drugs had no effect on contractions induced by a high concentration of KCl (160mM). The inhibitory effects of diazoxide and naringenin were blocked by glibenclamide. Oral administration of diazoxide and naringenin significantly reduced the intestinal transit of charcoal meal. The delay in the intestinal transit was blocked by the oral dose of glibenclamide. The effect of naringenin on the rat intestinal strip pre-contracted with the KCl was relatively similar to that of ATP-sensitive K+ channel opener (diazoxide). Conclusion: This research supports that ATP-sensitive K+ channels are involved in the rat small intestinal smooth muscles relaxation induced by naringenin.
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Affiliation(s)
- Hassan Sadraei
- Department of Pharmacology and Toxicology, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Maedeh Ghasemi
- Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Salman Saranji
- Department of Pharmacology and Toxicology, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
- Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
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Senik MH, Abu IF, Fadhullah W. Analysis of K ATP Channels Opening Probability of Hippocampus Cells Treated with Kainic Acid. Malays J Med Sci 2021; 28:15-26. [PMID: 33679216 PMCID: PMC7909348 DOI: 10.21315/mjms2021.28.1.3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 12/12/2020] [Indexed: 01/14/2023] Open
Abstract
Background Kainic acid (KA)-induced seizures may be a valuable tool in the assessment of anti-epileptic drug efficacy in complex partial seizures. This study investigated the effects of KA on ATP-sensitive K+ (KATP) channels opening probability (NPo), which plays a crucial role in neuronal activities. Methods For the optimisation and validation protocol, β-cells were plated onto 35 mm plastic petri dishes and maintained in RPMI-1640 media supplemented with 10 mM glucose, 10% FCS and 25 mM of N-2-hydroxyethylpiperazine-N-ethanesulfonic acid (HEPES). The treatment effects of 10 mM glucose and 30 μM fluoxetine on KATP channels NPo of β-cells were assessed via cell-attached patch-clamp recordings. For hippocampus cell experiments, hippocampi were harvested from day 17 of maternal Lister-hooded rat foetus, and then transferred to a Ca2+ and Mg2+-free HEPES-buffered Hank's salt solution (HHSS). The dissociated cells were cultured and plated onto a 25 mm round cover glasses coated with poly-d-lysine (0.1 mg/mL) in a petri dish. The KATP channels NPo of hippocampus cells when perfused with 1 mM and 10 mM of KA were determined. Results NPo of β-cells showed significant decreasing patterns (P < 0.001) when treated with 10 mM glucose 0.048 (0.027) as well as 30 μM fluoxetine 0.190 (0.141) as compared to basal counterpart. In hippocampus cell experiment, a significant increase (P < 0.001) in mean NPo 2.148 (0.175) of neurons when applied with 1 mM of KA as compared to basal was observed. Conclusion The two concentrations of KA used in the study exerted contrasting effects toward the mean of NPo. It is hypothesised that KA at lower concentration (1 mM) opens more KATP channels, leading to hyperpolarisation of the neurons, which may prevent neuronal hyper excitability. No effect was shown in 10 mM KA treatment, suggesting that only lower than 10 mM KA produced significant changes in KATP channels. This implies further validation of KA concentration to be used in the future.
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Affiliation(s)
- Mohd Harizal Senik
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Kelantan, Malaysia.,School of Life Sciences, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Izuddin Fahmy Abu
- Institute of Medical Science Technology, Universiti Kuala Lumpur, Kuala Lumpur, Malaysia
| | - Widad Fadhullah
- School of Industrial Technology, Universiti Sains Malaysia, Pulau Pinang, Malaysia
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Jackson WF. Introduction to ion channels and calcium signaling in the microcirculation. CURRENT TOPICS IN MEMBRANES 2020; 85:1-18. [PMID: 32402636 DOI: 10.1016/bs.ctm.2020.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The microcirculation is the network of feed arteries, arterioles, capillaries and venules that supply and drain blood from every tissue and organ in the body. It is here that exchange of heat, oxygen, carbon dioxide, nutrients, hormones, water, cytokines, and immune cells takes place; essential functions necessary to maintenance of homeostasis throughout the life span. This chapter will outline the structure and function of each microvascular segment highlighting the critical roles played by ion channels in the microcirculation. Feed arteries upstream from the true microcirculation and arterioles within the microcirculation contribute to systemic vascular resistance and blood pressure control. They also control total blood flow to the downstream microcirculation with arterioles being responsible for distribution of blood flow within a tissue or organ dependent on the metabolic needs of the tissue. Terminal arterioles control blood flow and blood pressure to capillary units, the primary site of diffusional exchange between blood and tissues due to their large surface area. Venules collect blood from capillaries and are important sites for fluid exchange and immune cell trafficking. Ion channels in microvascular smooth muscle cells, endothelial cells and pericytes importantly contribute to all of these functions through generation of intracellular Ca2+ and membrane potential signals in these cells.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, United States.
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Jackson WF. K V channels and the regulation of vascular smooth muscle tone. Microcirculation 2018; 25. [PMID: 28985443 DOI: 10.1111/micc.12421] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 10/01/2017] [Indexed: 12/31/2022]
Abstract
VSMCs in resistance arteries and arterioles express a diverse array of KV channels with members of the KV 1, KV 2 and KV 7 families being particularly important. Members of the KV channel family: (i) are highly expressed in VSMCs; (ii) are active at the resting membrane potential of VSMCs in vivo (-45 to -30 mV); (iii) contribute to the negative feedback regulation of VSMC membrane potential and myogenic tone; (iv) are activated by cAMP-related vasodilators, hydrogen sulfide and hydrogen peroxide; (v) are inhibited by increases in intracellular Ca2+ and vasoconstrictors that signal through Gq -coupled receptors; (vi) are involved in the proliferative phenotype of VSMCs; and (vii) are modulated by diseases such as hypertension, obesity, the metabolic syndrome and diabetes. Thus, KV channels participate in every aspect of the regulation of VSMC function in both health and disease.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, USA
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Tykocki NR, Boerman EM, Jackson WF. Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles. Compr Physiol 2017; 7:485-581. [PMID: 28333380 DOI: 10.1002/cphy.c160011] [Citation(s) in RCA: 222] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, Vermont, USA
| | - Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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Potassium Channels in Regulation of Vascular Smooth Muscle Contraction and Growth. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 78:89-144. [PMID: 28212804 DOI: 10.1016/bs.apha.2016.07.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Potassium channels importantly contribute to the regulation of vascular smooth muscle (VSM) contraction and growth. They are the dominant ion conductance of the VSM cell membrane and importantly determine and regulate membrane potential. Membrane potential, in turn, regulates the open-state probability of voltage-gated Ca2+ channels (VGCC), Ca2+ influx through VGCC, intracellular Ca2+, and VSM contraction. Membrane potential also affects release of Ca2+ from internal stores and the Ca2+ sensitivity of the contractile machinery such that K+ channels participate in all aspects of regulation of VSM contraction. Potassium channels also regulate proliferation of VSM cells through membrane potential-dependent and membrane potential-independent mechanisms. VSM cells express multiple isoforms of at least five classes of K+ channels that contribute to the regulation of contraction and cell proliferation (growth). This review will examine the structure, expression, and function of large conductance, Ca2+-activated K+ (BKCa) channels, intermediate-conductance Ca2+-activated K+ (KCa3.1) channels, multiple isoforms of voltage-gated K+ (KV) channels, ATP-sensitive K+ (KATP) channels, and inward-rectifier K+ (KIR) channels in both contractile and proliferating VSM cells.
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Pataricza J, Krassói I, Ambrus N, Bitay M, Varró A, Papp JG. Interspecies Differences and Extracellular Calcium Dependence in the Vasorelaxing Effect of Cromakalim in Isolated Human, Porcine, and Canine Coronary Arteries. J Cardiovasc Pharmacol Ther 2010; 15:289-95. [DOI: 10.1177/1074248409357744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Coronary arteries isolated from human, porcine, and canine hearts were depolarized with potassium chloride and relaxed by cromakalim (0.0125-10.0 μmol/L) at low (1.5 mmol/L) and high (7.5 mmol/L) extracellular calcium concentration ([Ca2+] o). At low [Ca2+]o, cromakalim (1 μmol/L) relaxed the coronary arteries with the order of porcine > canine > human. Fifty percent effective concentrations of cromakalim revealed the same order: 0.15 μmol/L in porcine, 0.36 μmol/L in canine, and 3.91 μmol/L in human coronary arteries. High [Ca2+]o significantly enhanced the relaxing effect and decreased the potency of cromakalim in porcine and human but not in canine coronary arteries. In human coronary arteries, precontracted with the prostaglandin analogue (U46619), high [Ca2+] o enhanced the effect of 0.1 μmol/L cromakalim more efficiently in the presence than in the absence of endothelium. It appears that the coronary dilating effect of cromakalim largely depends on the species and is modulated by [Ca2+]o, with a partly endothelium dependent manner.
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Affiliation(s)
- János Pataricza
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical Centre, University of Szeged, Szeged, Hungary,
| | - Irén Krassói
- Division of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Nora Ambrus
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical Centre, University of Szeged, Szeged, Hungary
| | - Miklós Bitay
- Division of Cardiac Surgery, 2nd Department of Internal Medicine, Albert Szent-Györgyi Medical Centre, University of Szeged, Szeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical Centre, University of Szeged, Szeged, Hungary
| | - Julius Gyula Papp
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical Centre, University of Szeged, Szeged, Hungary, Division of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
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Niinomi K, Banno Y, Iida H, Dohi S. Nicorandil, an Adenosine Triphosphate-Sensitive Potassium Channel Opener, Inhibits Muscarinic Acetylcholine Receptor-Mediated Activation of Extracellular Signal-Regulated Kinases in PC12 Cells. Anesth Analg 2008; 107:1892-8. [DOI: 10.1213/ane.0b013e31818880a8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Takemoto J, Masumiya H, Nunoki K, Sato T, Nakagawa H, Ikeda Y, Arai Y, Yanagisawa T. Potentiation of potassium currents by beta-adrenoceptor agonists in human urinary bladder smooth muscle cells: a possible electrical mechanism of relaxation. Pharmacology 2008; 81:251-8. [PMID: 18253064 DOI: 10.1159/000114719] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Accepted: 10/10/2007] [Indexed: 11/19/2022]
Abstract
We examined the effects of beta-adrenoceptor agonists on the membrane currents of smooth muscle cells from the human urinary bladder using a whole-cell patch clamp to investigate the involvement of Ca(2+)-activated K(+) (K(Ca)) channels in relaxation by beta-adrenergic agonists. With 0.05 mmol/l EGTA in the patch pipette, depolarizing pulses evoked outward rectifying currents. Isoproterenol (1 micromol/l) significantly increased the membrane currents by 75% at +80 mV with 0.05 mmol/l EGTA pipette solution. BRL 37344 (1 micromol/l) significantly increased the membrane currents by 44% at +80 mV. Iberiotoxin (100 nmol/l) significantly decreased the membrane currents by 60% at +80 mV. In the presence of iberiotoxin, the potentiation of the outward currents by isoproterenol was greatly suppressed and, in the presence of iberiotoxin and apamin (1 micromol/l), the potentiation by isoproterenol was totally abolished. On the other hand, with 5 mmol/l EGTA pipette solution, depolarizing pulses evoked smaller outward currents. Isoproterenol (1 micromol/l) did not change the membrane currents with 5 mmol/l EGTA pipette solution. The real-time PCR analysis revealed the expression of beta(2)-adrenoceptors in the cells. These results suggest that Ca(2+)-activated and iberiotoxin- and apamin-sensitive currents via both large-conductance and small-conductance K(Ca) channels could be increased by stimulation of beta(2)-adrenoceptors.
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Affiliation(s)
- Jun Takemoto
- Department of Molecular Pharmacology, Graduate School of Medicine, Tohoku University, Sendai, Japan
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Stojnic N, Gojkovic-Bukarica L, Peric M, Grbovic L, Lesic A, Bumbasirevic M, Heinle H. Potassium channel opener pinacidil induces relaxation of the isolated human radial artery. J Pharmacol Sci 2007; 104:122-9. [PMID: 17538231 DOI: 10.1254/jphs.fp0061434] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Taking into consideration that the search for drugs capable of modifying blood flow through human radial artery (RA) is warranted, the present study was designed to examine the vasodilatatory effects of the potassium channel opener, pinacidil on the RA and to define the contribution of different K+ -channel subtypes in the endothelium-independent pinacidil action on this blood vessel. Pinacidil relaxed the RA rings with endothelium and without endothelium with comparable potency. N-nitro-L-arginine methyl ester (L-NAME) and methylene blue did not affect the pinacidil-induced vasorelaxation in rings with endothelium. In the rings without endothelium, the K+ -channel blockers glibenclamide and tetraethylammonium (TEA) moderately antagonized the pinacidil-induced relaxation, while charybdotoxin and 4-aminopiridine did not. In endothelium-denuded rings, precontracted with 100 mM K+, the relaxant responses to pinacidil were highly significantly shifted to the right compared to those obtained in RA precontracted with phenylephrine, but pinacidil-induced maximal relaxation was not affected. Addition of nifedipine did not but addition of nifedipine and nickel (Na+ -Ca2+ exchanger inhibitor) did cause a statistically significant rightward shift of the pinacidil concentration-relaxation curve, although the effect 0.1 mM pinacidil was preserved. Thus, pinacidil induces relaxation of the human RA in endothelium-independent manner, and glibenclamide- and TEA-sensitive vascular smooth muscle K+ channels are probably involved. Its ability to completely relax the RA precontracted with K+ -rich solution suggests that pinacidil has additional K+ channel-independent mechanism(s) of action. It seems that stimulation of the forward mode of the Na+ -Ca2+ exchanger plays a part in this K+ channel-independent effect of pinacidil.
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Affiliation(s)
- Natasa Stojnic
- Department of Clinical Pharmacology, Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, Belgrade 11129, Serbia
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Sahara M, Takahashi T, Imai Y, Nakajima T, Yao A, Morita T, Hirata Y, Nagai R. New Insights in the Treatment Strategy for Pulmonary Arterial Hypertension. Cardiovasc Drugs Ther 2006; 20:377-86. [PMID: 17124557 DOI: 10.1007/s10557-006-0498-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Recent advances in our understanding of the pathophysiological and molecular mechanisms involved in pulmonary arterial hypertension have led to the development of novel and rational pharmacological therapies. In addition to conventional therapy (i.e., supplemental oxygen and calcium channel blockers), prostacyclin or endothelin receptor antagonists have been recommended as a first-line therapy for pulmonary arterial hypertension. However, these treatments have potential limitations with regard to their long-term efficacy and improvement in survival. Furthermore, intravenous prostacyclin (epoprostenol) therapy, which is recommended by most experts for patients with New York Heart Association (NYHA) functional class IV, is complicated, uncomfortable for patients, and expensive because of the cumbersome administration system. Considering these circumstances, it is necessary to develop additional novel therapeutic approaches that target the various components of this multifactorial disease. CASE REPORT In this short review, we present an overview of the current treatment options for pulmonary arterial hypertension and describe a case report with primary pulmonary hypertension. A male patient with NYHA functional class IV and showing no response to calcium channel blockers and prostacyclin exhibited significantly improved exercise tolerance and hemodynamics and long-term survival for more than 2.5 years after receiving an oral combination therapy of a phosphodiesterase type 5 inhibitor (sildenafil), phosphodiesterase type 3 inhibitor (pimobendan), and nicorandil. FUTURE PERSPECTIVE We also discuss the background and plausible potential mechanisms involved in this case, as well as future perspectives in the treatment of pulmonary arterial hypertension.
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Affiliation(s)
- Makoto Sahara
- Department of Cardiovascular Medicine, University of Tokyo Graduate School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
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Hirota S, Pertens E, Janssen LJ. The reverse mode of the Na(+)/Ca(2+) exchanger provides a source of Ca(2+) for store refilling following agonist-induced Ca(2+) mobilization. Am J Physiol Lung Cell Mol Physiol 2006; 292:L438-47. [PMID: 17041014 DOI: 10.1152/ajplung.00222.2006] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Agonist-induced contraction of airway smooth muscle (ASM) can be triggered by an elevation in the intracellular Ca(2+) concentration, primarily through the release of Ca(2+) from the sarcoplasmic reticulum (SR). The refilling of the SR is integral for subsequent contractions. It has been suggested that Ca(2+) entry via store-operated cation (SOC) and receptor-operated cation channels may facilitate refilling of the SR. Indeed, depletion of the SR activates substantial inward SOC currents in ASM that are composed of both Ca(2+) and Na(+). Accumulation of Na(+) within the cell may regulate Ca(2+) handling in ASM by forcing the Na(+)/Ca(2+) exchanger (NCX) into the reverse mode, leading to the influx of Ca(2+) from the extracellular domain. Since depletion of the SR activates substantial inward Na(+) current, it is conceivable that the reverse mode of the NCX may contribute to the intracellular Ca(2+) pool from which the SR is refilled. Indeed, successive contractions of bovine ASM, evoked by various agonists (ACh, histamine, 5-HT, caffeine) were significantly reduced upon removal of extracellular Na(+); whereas contractions evoked by KCl were unchanged by Na(+) depletion. Ouabain, a selective inhibitor of the Na(+)/K(+) pump, had no effect on the reductions observed under normal and zero-Na(+) conditions. KB-R7943, a selective inhibitor of the reverse mode of the NCX, significantly reduced successive contractions induced by all agonists without altering KCl responses. Furthermore, KB-R7943 abolished successive caffeine-induced Ca(2+) transients in single ASM cells. Together, these data suggest a role for the reverse mode of the NCX in refilling the SR in ASM following Ca(2+) mobilization.
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Affiliation(s)
- Simon Hirota
- Asthma Research Group, Firestone Institute for Respiratory Health, St. Joseph's Healthcare, and Department of Medicine, McMaster University, Hamilton, Ontario, Canada
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Abstract
Vascular smooth muscle (VSM) cells, endothelial cells (EC), and pericytes that form the walls of vessels in the microcirculation express a diverse array of ion channels that play an important role in the function of these cells and the microcirculation in both health and disease. This brief review focuses on the K+ channels expressed in smooth muscle and endothelial cells in arterioles. Microvascular VSM cells express at least four different classes of K+ channels, including inward-rectifier K+ channels (Kin), ATP-sensitive K+ channels (KATP), voltage-gated K+ channels (Kv), and large conductance Ca2+-activated K+ channels (BKCa). VSM KIR participate in dilation induced by elevated extracellular K+ and may also be activated by C-type natriuretic peptide, a putative endothelium-derived hyperpolarizing factor (EDHF). Vasodilators acting through cAMP or cGMP signaling pathways in VSM may open KATP, Kv, and BKCa, causing membrane hyperpolarization and vasodilation. VSMBKc. may also be activated by epoxides of arachidonic acid (EETs) identified as EDHF in some systems. Conversely, vasoconstrictors may close KATP, Kv, and BKCa through protein kinase C, Rho-kinase, or c-Src pathways and contribute to VSM depolarization and vasoconstriction. At the same time Kv and BKCa act in a negative feedback manner to limit depolarization and prevent vasospasm. Microvascular EC express at least 5 classes of K+ channels, including small (sKCa) and intermediate(IKCa) conductance Ca2+-activated K+ channels, Kin, KATP, and Kv. Both sK and IK are opened by endothelium-dependent vasodilators that increase EC intracellular Ca2+ to cause membrane hyper-polarization that may be conducted through myoendothelial gap junctions to hyperpolarize and relax arteriolar VSM. KIR may serve to amplify sKCa- and IKCa-induced hyperpolarization and allow active transmission of hyperpolarization along EC through gap junctions. EC KIR channels may also be opened by elevated extracellular K+ and participate in K+-induced vasodilation. EC KATP channels may be activated by vasodilators as in VSM. Kv channels may provide a negative feedback mechanism to limit depolarization in some endothelial cells.
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Affiliation(s)
- William F Jackson
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI 49008-5410, USA.
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15
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Tsang SY, Yao X, Wong CM, Au CL, Chen ZY, Huang Y. Contribution of Na+ -Ca2+ exchanger to pinacidil-induced relaxation in the rat mesenteric artery. Br J Pharmacol 2003; 138:453-60. [PMID: 12569070 PMCID: PMC1573686 DOI: 10.1038/sj.bjp.0705062] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1 Pinacidil relaxes blood vessels through opening the K(ATP) channels with a resultant membrane hyperpolarization and inhibition of Ca(2+) influx. The aim of this study was to examine the mechanisms thereby pinacidil induces K(+) channel-independent relaxation in isolated endothelium-denuded rat mesenteric artery. 2 Pinacidil-induced relaxation was inhibited by glibenclamide (1-10 micro M) in phenylephrine-preconstricted rings, but was unaffected by glibenclamide after inhibition of K(+) channels and VGCCs. Pinacidil-induced K(+) channel-independent relaxation remained unchanged after treatment with cyclopiazonic acid (10 micro M), thapsigargin (1 micro M), ouabain (100 micro M), propranolol (10 micro M), Rp-cAMPS triethylamine (30 micro M), L-NNA (100 micro M), or ODQ (10 micro M). 3 Pinacidil induced more relaxant effect in the presence of nifedipine than in the presence of 60 mM K(+) plus nifedipine. Pretreatment with Na(+)-Ca(2+) exchanger inhibitors, nickel (30-300 micro M) or benzamil (20 micro M) attenuated pinacidil-induced relaxation in normal or in nifedipine-containing solution. Pinacidil (1 micro M) produced less relaxant effect with decreasing extracellular Na(+) concentration. Na(+)-free condition abolished the inhibitory effect of benzamil. Both nickel and benzamil inhibited pinacidil-induced relaxation in the presence of glibenclamide (10 micro M). Nickel (300 micro M) did not affect the relaxant response to sodium nitroprusside. 4 Pinacidil relaxed the rings preconstricted by active phorbol and U46619 with similar potency. 5 The present results indicate that stimulation of the forward mode Na(+)-Ca(2+) exchange pathway is in part responsible for pinacidil-induced K(+) channel-independent vasorelaxation. Pinacidil also induces K(+) channel-dependent but VGCCs-independent relaxation. The PKC-mediated cellular pathway may be a target site for pinacidil only in higher concentrations.
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Affiliation(s)
- Suk Ying Tsang
- Department of Physiology, Chinese University of Hong Kong, Hong Kong, China
| | - Xiaoqiang Yao
- Department of Physiology, Chinese University of Hong Kong, Hong Kong, China
| | - Chi Ming Wong
- Department of Physiology, Chinese University of Hong Kong, Hong Kong, China
| | - Chak Leung Au
- Department of Physiology, Chinese University of Hong Kong, Hong Kong, China
| | - Zhen Yu Chen
- Department of Biochemistry, Chinese University of Hong Kong, Hong Kong, China
| | - Yu Huang
- Department of Physiology, Chinese University of Hong Kong, Hong Kong, China
- Author for correspondence:
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16
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Shimamura K, Yamamoto K, Sekiguchi F, Sunano S. Altered beta-adrenoceptor-mediated responses in the gastric smooth muscle of hypertensive rats. J Smooth Muscle Res 2000; 36:1-12. [PMID: 10830473 DOI: 10.1540/jsmr.36.1] [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: 11/13/2022] Open
Abstract
Effects of isoproterenol on contraction and membrane potential of gastric smooth muscle were studied in stroke prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar Kyoto rats (WKY). Circular muscle preparation from the gastric fundus developed tonic contraction by re administration of Ca2+ to a nominally Ca2+-free solution. The contraction was inhibited by nifedipine or nicardipine. Isoproterenol induced relaxation when it was applied to the Ca2+-induced contraction. The amplitude of isoproterenol induced relaxation was concentration-dependent. Propranolol 10(-6) M abolished the relaxation induced by isoproterenol 10(-7) M. In the preparation from SHRSP, the amplitude of isoproterenol induced relaxation was smaller than that from WKY between 3 x 10(-9) and 10(-7) M. Forskolin, an adenylate cyclase activator, induced concentration-dependent relaxation. There was no difference in the relaxation induced by forskolin between preparations from WKY and SHRSP. Dibutilyl cyclic AMP, a membrane permeable analogue of cyclic AMP, also induced similar relaxation in preparations from WKY and SHRSP. Resting membrane potential of smooth muscle cell was not different between preparations from WKY and SHRSP. Isoproterenol hyperpolarized the membrane concentration-dependently. Isoproterenol-induced hyperpolarization in the preparation from SHRSP was smaller than that from WKY between 10(-8) and 10(-6) M. When the membrane was depolarized by Tyrode's solution containing 40 mM K+, isoproterenol-induced hyperpolarization was almost abolished. In this condition, the isoproterenol-induced relaxation was inhibited partly, however, there was no difference in the amplitude of relaxation between preparations from WKY and SHRSP. Therefore, isoproterenol-induced hyperpolarization contributed at least partly to the relaxation. Forskolin hyperpolarized the membrane by the same amplitude in the preparations from WKY and SHRSP. These results indicate that a decrease in hyperpolarization may contribute to the decreased relaxation by isoproterenol in the preparation from SHRSP.
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Affiliation(s)
- K Shimamura
- Research Institute of Hypertension, Kinki University, Osaka-Sayama, Japan
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17
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Asano M, Nakajima T, Hazama H, Iwasawa K, Tomaru T, Omata M, Soma M, Asakura Y, Mizutani M, Suzuki S, Yamashita K, Okuda Y. Influence of cellular incorporation of n-3 eicosapentaenoic acid on intracellular Ca2+ concentration and membrane potential in vascular smooth muscle cells. Atherosclerosis 1998; 138:117-27. [PMID: 9678777 DOI: 10.1016/s0021-9150(98)00010-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Long-term treatment with n-3 eicosapentaenoic acid (EPA) has been shown to exert hypotensive effects and have beneficial effects on atherosclerosis. To elucidate one of the underlying mechanisms of these effects, intracellular calcium concentration [Ca2+]i, and resting membrane potential were measured in rat vascular smooth muscle cells (A7r5 cell) treated with EPA, using Ca2+-sensitive dye fura-2 AM and the patch clamp technique. The alterations in fatty acid compositions of phospholipids and cell migration after treatment with EPA (30 microM) for 6 h-7 days were also examined. After treating cells with EPA, the EPA and DPA (docosapentaenoic acid) content of the phospholipid fraction (mol.%) increased in a time-dependent manner. Alternatively, arachidonic acid (AA) decreased, and then the ratio of EPA and AA (EPA/AA) increased significantly. The resting [Ca2+]i decreased from 170 +/- 46 nM (n = 16) in control cells to 123 +/- 29 nM (n = 16) in cells treated with EPA (30 microM) for 7 days. Vasopressin (100 nM), endothelin-1 (100 nM) and platelet-derived growth factor (PDGF 5 ng/ml) evoked an initial peak of [Ca2+]i, followed by a smaller sustained rise of [Ca2+]i in the presence of extracellular Ca2+. In EPA-treated cells, both the peak and the sustained rise of [Ca2+]i induced by these agonists decreased in comparison to the control cells. EPA treatment also decreased the transient [Ca2+]i rise evoked by these agonists in the absence of extracellular Ca2+. Under the current clamp condition, resting membrane potential was significantly higher in EPA-treated cells (-49.8 +/- 10.4 mV, n = 41) than in control cells (-44.6 +/- 7.4 mV, n = 41, P < 0.05), and the input resistance of the cell was lower in EPA-treated cells, while cell size and capacitance were not statistically different. In addition, long-term treatment with EPA for 7 days significantly inhibited PDGF-induced cell migration. These results suggest that cellular incorporation of n-3 eicosapentaenoic acid attenuates intracellular mechanisms related to changes of [Ca2+]i and affects membrane potential, thereby inhibiting migration of vascular smooth muscle cells. These actions of EPA may contribute to its vasorelaxant and antiatherosclerotic effects.
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Affiliation(s)
- M Asano
- Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan
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Higashino R, Sato R, Jin H, Inoue N, Fukuta Y, Kurimoto T, Tamaki H. Inhibitory effects of efonidipine hydrochloride on contraction induced by several vasoconstrictors in porcine coronary artery: comparison with effects of nifedipine and nisoldipine. J Cardiovasc Pharmacol 1997; 29:624-30. [PMID: 9213205 DOI: 10.1097/00005344-199705000-00010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We studied the effects of efonidipine hydrochloride (efonidipine), a 1,4-dihydropyridine derivative, on contractions induced by high-K+ solution (high K+), serotonin (5-HT), U46619, which is a stable analog of thromboxane A2, and endothelin-1 (ET-1) in comparison with those of nifedipine and nisoldipine in porcine coronary arteries. The effects of the drugs were compared after 1- and 3-h incubations. Efonidipine, nifedipine, and nisoldipine each inhibited the contractions induced by these vasoconstrictors. The inhibition of high-K(+)- and 5-HT-induced contractions by efonidipine, but not by nifedipine and nisoldipine, increased when the incubation time was prolonged, whereas the inhibition of U46619- and ET-1-induced contractions was not altered. The potency of efonidipine on U46619- and ET-1-induced contractions was greater than that of nifedipine and equivalent to that of nisoldipine. Thus the inhibitory effect of efonidipine on U46619- and ET-1-induced contractions seems to be stronger than its effects on high-K(+)- or 5-HT-induced contractions, in contrast to the effects of other dihydropyridines. In an additional series of experiments, efonidipine did not inhibit U46619-induced contractions in Ca2(+)-free solution or in the presence of nifedipine. Moreover, efonidipine did not inhibit the specific binding of [3H]SQ 29,548, a thromboxane A2 antagonist, to porcine coronary arterial membrane. Therefore we think that the inhibitory effect of efonidipine on contractions induced by vasoconstrictors was caused by blockade of Ca2+ influx through L-type Ca2+ channels. However, some unknown mechanism(s) in addition to this effect on Ca2+ channels may contribute to the effect of efonidipine on U46619- and ET-1-induced contractions.
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Affiliation(s)
- R Higashino
- Central Research Laboratories, Zeria Pharmaceutical Co., Ltd., Saitama, Japan
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Prestwich SA, Bolton TB. Inhibition of muscarinic receptor-induced inositol phospholipid hydrolysis by caffeine, beta-adrenoceptors and protein kinase C in intestinal smooth muscle. Br J Pharmacol 1995; 114:602-11. [PMID: 7537591 PMCID: PMC1510025 DOI: 10.1111/j.1476-5381.1995.tb17182.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
1. The effects of caffeine, isoprenaline, dibutyryl cyclic AMP, isobutylmethylxanthine (IBMX), 12-O-tetradecanoylphorbol-13-acetate (TPA) or 1-oleoyl-2-acetylglycerol (OAG), (protein kinase C (PKC) activators), 2-methoxy verapamil (D600), thapsigargin and ryanodine on muscarinic acetylcholine receptor (AChR)-stimulated inositol phospholipid hydrolysis were studied in smooth muscle fragments from the longitudinal layer of the small intestine of the guinea-pig. 2. Incubation of the fragments with the muscarinic agonist, carbachol (CCh) (100 microM) resulted in rapid increases in the levels of all the inositol phosphate isomers with maximal increases in the [3H]-inositol (1,4,5) trisphosphate ([3H]-Ins(1,4,5)P3) isomer occurring 10 s following incubation. 3. The beta-adrenoceptor agonist, isoprenaline (10 microM) and dibutyryl cyclic AMP (10 microM), a membrane permeant analogue of cyclic AMP both reduced the CCh stimulation, but not the basal levels of [3H]-inositol phosphates. This inhibition by dibutyryl cyclic AMP was enhanced in the presence of the phosphodiesterase inhibitor, IBMX. CCh inhibited the isoprenaline-induced increases in the levels of cyclic AMP and this was via a pertussi toxin (PTX)-sensitive G-protein mechanism. 4. TPA (1 microM) and OAG (100 microM) a 1,2-diacylglycerol (DAG) analogue both reduced the CCh-induced increases in [3H]-inositol phosphates levels but neither affected basal values nor the basal levels of cyclic AMP. 5. D600 (10 microM), which blocks voltage-dependent Ca2+ channels, also reduced the CCh-stimulated levels of [3H]-inositol phosphates suggesting that some of the agonist-induced increases are due to a potentiating effect of Ca2+ entering the cell. 6. Caffeine (0.5-30 mM) significantly inhibited both the basal and CCh-induced increases in all the [3H]-inositol phosphate isomers. Its inhibitory action was not due to increases in cyclic AMP since caffeine had no effect on the levels of cyclic AMP at concentrations up to 30 mM. 7. Incubation with thapsigargin (1 microM) and ryanodine (10 microM) had no effect on either basal or CCh-induced inositol phospholipid hydrolysis or cyclic AMP levels. 8. The results indicate a reciprocal inhibition by beta-adrenoceptors and muscarinic AChRs of their effects on cyclic AMP and inositol phosphate levels respectively. Ca2+ entering the cell (but not the action of ryanodine or thapsigargin) potentiates while caffeine inhibits muscarinic AChR-induced rises in inositol phosphate levels. Diacylglycerols may exert a negative feedback inhibition on inositol phosphate production.
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MESH Headings
- 1-Methyl-3-isobutylxanthine/pharmacology
- Animals
- Bucladesine/pharmacology
- Caffeine/pharmacology
- Calcium Channels/drug effects
- Calcium-Transporting ATPases/antagonists & inhibitors
- Carbachol/pharmacology
- Cyclic AMP/metabolism
- Diglycerides/pharmacology
- Gallopamil/pharmacology
- Guinea Pigs
- Hydrolysis
- In Vitro Techniques
- Inositol 1,4,5-Trisphosphate/metabolism
- Intestine, Small/drug effects
- Intestine, Small/metabolism
- Isoproterenol/pharmacology
- Muscle, Smooth/drug effects
- Muscle, Smooth/metabolism
- Protein Kinase C/metabolism
- Receptors, Adrenergic, beta/drug effects
- Receptors, Adrenergic, beta/physiology
- Receptors, Muscarinic/drug effects
- Receptors, Muscarinic/metabolism
- Ryanodine/pharmacology
- Stereoisomerism
- Terpenes/pharmacology
- Tetradecanoylphorbol Acetate/pharmacology
- Thapsigargin
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Affiliation(s)
- S A Prestwich
- Department of Pharmacology and Clinical Pharmacology, St. George's Hospital Medical School, London
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