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Shafaroodi H, Barati S, Ghasemi M, Almasirad A, Moezi L. A role for ATP-sensitive potassium channels in the anticonvulsant effects of triamterene in mice. Epilepsy Res 2016; 121:8-13. [PMID: 26855365 DOI: 10.1016/j.eplepsyres.2016.01.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Revised: 01/05/2016] [Accepted: 01/16/2016] [Indexed: 12/13/2022]
Abstract
There are reports indicating that diuretics including chlorothiazide, furosemide, ethacrynic acid, amiloride and bumetanide can have anticonvulsant properties. Intracellular acidification appears to be a mechanism for the anticonvulsant action of some diuretics. This study was conducted to investigate whether or not triamterene, a K(+)-sparing diuretic, can generate protection against seizures induced by intravenous or intraperitoneal pentylenetetrazole (PTZ) models. And to see if, triamterene can withstand maximal electroshock seizure (MES) in mice. We also investigated to see if there is any connection between triamterene's anti-seizure effect and ATP-sensitive K(+) (KATP) channels. Five days triamterene oral administration (10, 20 and 40 mg/kg), significantly increased clonic seizure threshold which was induced by intravenous pentylenetetrazole. Triamterene (10, 20 and 40 mg/kg) treatment also increased the latency of clonic seizure and decreased its frequency in intraperitoneal PTZ model. Administration of triamterene (20 mg/kg) also decreased the incidence of tonic seizure in MES-induced seizure. Co-administration of a KATP sensitive channel blocker, glibenclamide, in the 6th day, 60 min before intravenous PTZ blocked triamterene's anticonvulsant effect. A KATP sensitive channel opener, diazoxide, enhanced triamterene's anti-seizure effect in both intravenous PTZ or MES seizure models. At the end, triamterene exerts anticonvulsant effect in 3 seizure models of mice including intravenous PTZ, intraperitoneal PTZ and MES. The anti-seizure effect of triamterene probably is induced through KATP channels.
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Affiliation(s)
- Hamed Shafaroodi
- Department of Pharmacology and Toxicology, Pharmaceutical Sciences Branch and Pharmaceutical Sciences Research Center, Islamic Azad University, Tehran, Iran
| | - Saghar Barati
- Department of Pharmacology and Toxicology, Pharmaceutical Sciences Branch and Pharmaceutical Sciences Research Center, Islamic Azad University, Tehran, Iran
| | - Mehdi Ghasemi
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Ali Almasirad
- Department of Medicinal Chemistry, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran, Iran
| | - Leila Moezi
- Department of Pharmacology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran; Nanomedicine and Nanobiology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
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Abstract
PURPOSE/AIM Changes in pH are not infrequently encountered in clinical situations and can be associated with significant effects on ion channels, mitochondria and axon function. The purpose of this paper is to study the modulatory effects of pH on the anoxic response in peripheral nerve. MATERIALS AND METHODS A total of 48 rat sciatic nerves were studied in vitro in a perfusion apparatus. Experiments were carried out at 6 pH levels from 6.0 to 7.8. RESULTS The amplitude of the nerve action potential (NAP) drops more dramatically with repetitive periods of anoxia when the pH is reduced below 6.5. In addition, velocity decreases and duration increases more with each cycle of anoxia at low pH values. Despite these effects of pH on recovery after anoxia, there was no significant effect of pH on the time course of changes during anoxia. During recovery from anoxia, the NAP recovered more slowly when the pH was lowered. CONCLUSIONS The pattern of changes in amplitude, velocity and duration suggest that they may be due to interference of high hydrogen ion concentrations with sodium and potassium channel function.
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Browning KN. Modulation of gastrointestinal vagal neurocircuits by hyperglycemia. Front Neurosci 2013; 7:217. [PMID: 24324393 PMCID: PMC3840437 DOI: 10.3389/fnins.2013.00217] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 10/30/2013] [Indexed: 12/17/2022] Open
Abstract
Glucose sensing within autonomic neurocircuits is critical for the effective integration and regulation of a variety of physiological homeostatic functions including the co-ordination of vagally-mediated reflexes regulating gastrointestinal (GI) functions. Glucose regulates GI functions via actions at multiple sites of action, from modulating the activity of enteric neurons, endocrine cells, and glucose transporters within the intestine, to regulating the activity and responsiveness of the peripheral terminals, cell bodies and central terminals of vagal sensory neurons, to modifying both the activity and synaptic responsiveness of central brainstem neurons. Unsurprisingly, significant impairment in GI functions occurs in pathophysiological states where glucose levels are dysregulated, such as diabetes. A substantial obstacle to the development of new therapies to modify the disease, rather than treat the symptoms, are the gaps in our understanding of the mechanisms by which glucose modulates GI functions, particularly vagally-mediated responses and a more complete understanding of disease-related plasticity within these neurocircuits may open new avenues and targets for research.
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Affiliation(s)
- Kirsteen N Browning
- Department of Neural and Behavioral Sciences, Penn State College of Medicine Hershey, PA, USA
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Autonomic Nervous System In Vitro: Studying Tonically Active Neurons Controlling Vagal Outflow in Rodent Brainstem Slices. ISOLATED CENTRAL NERVOUS SYSTEM CIRCUITS 2012. [DOI: 10.1007/978-1-62703-020-5_1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Togami K, Chono S, Morimoto K. Distribution characteristics of clarithromycin and azithromycin, macrolide antimicrobial agents used for treatment of respiratory infections, in lung epithelial lining fluid and alveolar macrophages. Biopharm Drug Dispos 2011; 32:389-97. [DOI: 10.1002/bdd.767] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Revised: 06/27/2011] [Accepted: 07/01/2011] [Indexed: 11/09/2022]
Affiliation(s)
- Kohei Togami
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences; Hokkaido Pharmaceutical University; 7-1, Katsuraoka-cho; Otaru; Hokkaido; 047-0264; Japan
| | - Sumio Chono
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences; Hokkaido Pharmaceutical University; 7-1, Katsuraoka-cho; Otaru; Hokkaido; 047-0264; Japan
| | - Kazuhiro Morimoto
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences; Hokkaido Pharmaceutical University; 7-1, Katsuraoka-cho; Otaru; Hokkaido; 047-0264; Japan
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Kornhuber J, Henkel AW, Groemer TW, Städtler S, Welzel O, Tripal P, Rotter A, Bleich S, Trapp S. Lipophilic cationic drugs increase the permeability of lysosomal membranes in a cell culture system. J Cell Physiol 2010; 224:152-64. [PMID: 20301195 DOI: 10.1002/jcp.22112] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Lysosomes accumulate many drugs several fold higher compared to their extracellular concentration. This mechanism is believed to be responsible for many pharmacological effects. So far, uptake and release kinetics are largely unknown and interactions between concomitantly administered drugs often provoke mutual interference. In this study, we addressed these questions in a cell culture model. The molecular mechanism for lysosomal uptake kinetics was analyzed by live cell fluorescence microscopy in SY5Y cells using four drugs (amantadine, amitriptyline, cinnarizine, flavoxate) with different physicochemical properties. Drugs with higher lipophilicity accumulated more extensively within lysosomes, whereas a higher pK(a) value was associated with a more rapid uptake. The drug-induced displacement of LysoTracker was neither caused by elevation of intra-lysosomal pH, nor by increased lysosomal volume. We extended our previously developed numerical single cell model by introducing a dynamic feedback mechanism. The empirical data were in good agreement with the results obtained from the numerical model. The experimental data and results from the numerical model lead to the conclusion that intra-lysosomal accumulation of lipophilic xenobiotics enhances lysosomal membrane permeability. Manipulation of lysosomal membrane permeability might be useful to overcome, for example, multi-drug resistance by altering subcellular drug distribution.
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Affiliation(s)
- Johannes Kornhuber
- Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Erlangen, Germany.
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Judge SIV, Smith PJ. Patents related to therapeutic activation of K(ATP) and K(2P) potassium channels for neuroprotection: ischemic/hypoxic/anoxic injury and general anesthetics. Expert Opin Ther Pat 2009; 19:433-60. [PMID: 19441925 DOI: 10.1517/13543770902765151] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND Mechanisms of neuroprotection encompass energy deficits in brain arising from insufficient oxygen and glucose levels following respiratory failure; ischemia or stroke, which produce metabolic stresses that lead to unconsciousness and seizures; and the effects of general anesthetics. Foremost among those K(+) channels viewed as important for neuroprotection are ATP-sensitive (K(ATP)) channels, which belong to the family of inwardly rectifying K(+) channels (K(ir)) and contain a sulfonylurea subunit (SUR1 or SUR2) combined with either K(ir)6.1 (KCNJ8) or K(ir)6.2 (KCNJ11) channel pore-forming alpha-subunits, and various members of the tandem two-pore or background (K(2P)) K(+) channel family, including K(2P)1.1 (KCNK1 or TWIK1), K(2P)2.1 (KCNK2 or TREK/TREK1), K(2P)3.1 (KCNK3 or TASK), K(2P)4.1 (KCNK4 or TRAAK), and K(2P)10.1 (KCNK10 or TREK2). OBJECTIVES This review covers patents and patent applications related to inventions of therapeutics, compound screening methods and diagnostics, including K(ATP) channel openers and blockers, as well as K(ATP) and K(2P) nucleic/amino acid sequences and proteins, vectors, transformed cells and transgenic animals. Although the focus of this patent review is on brain and neuroprotection, patents covering inventions of K(ATP) channel openers for cardioprotection, diabetes mellitus and obesity, where relevant, are addressed. RESULTS/CONCLUSIONS Overall, an important emerging therapeutic mechanism underlying neuroprotection is activation/opening of K(ATP) and K(2P) channels. To this end substantial progress has been made in identifying and patenting agents that target K(ATP) channels. However, current K(2P) channels patents encompass compound screening and diagnostics methodologies, reflecting an earlier 'discovery' stage (target identification/validation) than K(ATP) in the drug development pipeline; this reveals a wide-open field for the discovery and development of K(2P)-targeting compounds.
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Affiliation(s)
- Susan I V Judge
- University of Maryland School of Medicine, MS Center of Excellence-East, VA Maryland Health Care System, Department of Neurology, BRB 12-040, 655 West Baltimore Street, Baltimore, MD 21201, USA
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Niaki SEA, Shafaroodi H, Ghasemi M, Shakiba B, Fakhimi A, Dehpour AR. Mouth breathing increases the pentylenetetrazole-induced seizure threshold in mice: a role for ATP-sensitive potassium channels. Epilepsy Behav 2008; 13:284-9. [PMID: 18508411 DOI: 10.1016/j.yebeh.2008.04.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 04/13/2008] [Accepted: 04/18/2008] [Indexed: 10/22/2022]
Abstract
Nasal obstruction and consequent mouth breathing have been shown to change the acid-base balance, producing respiratory acidosis. Additionally, there exists a large body of evidence maintaining that acidosis affects the activity of ATP-sensitive potassium (K(ATP)) channels, which play a crucial role in the function of the central nervous system (CNS), for example, in modulating seizure threshold. Thus, in the study described here, we examined whether mouth breathing, induced by surgical ligation of nostrils, could affect the seizure threshold induced by pentylenetetrazole in male NMRI mice. Using the selective K(ATP) channel opener (diazoxide) and blocker (glibenclamide), we also evaluated the possible role of K(ATP) channels in this process. Our data revealed that seizure threshold was increased 6 to 72 hours after nasal obstruction, reaching a peak 48 hours afterward, compared with either control or sham-operated mice (P<0.01). There was a significant decrease in pH of arterial blood samples and increase in CO(2) partial pressure (PCO(2)) during this time. Systemic injection of glibenclamide (1 and 2mg/kg, ip, daily) significantly prevented the increase in seizure threshold in 48-hour bilaterally nasally obstructed mice, whereas it had no effect on seizure threshold in sham-operated mice. Systemic injection of diazoxide (25mg/kg, ip, daily) had no effect on seizure threshold in all groups, whereas higher doses (50 and 100mg/kg, ip, daily) significantly increased seizure threshold in both 48-hour-obstructed and sham-operated mice. The decrease in seizure threshold induced by glibenclamide (2mg/kg, ip, daily) was prevented by diazoxide (25mg/kg, ip, daily). These results demonstrate for the first time that mouth breathing, which could result in respiratory acidosis, increases seizure threshold in mice and K(ATP) channels may play a role in this effect.
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Henrich M, Buckler KJ. Effects of anoxia, aglycemia, and acidosis on cytosolic Mg2+, ATP, and pH in rat sensory neurons. Am J Physiol Cell Physiol 2007; 294:C280-94. [PMID: 17977942 DOI: 10.1152/ajpcell.00345.2007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sensory neurons can detect ischemia and transmit pain from various organs. Whereas the primary stimulus in ischemia is assumed to be acidosis, little is known about how the inevitable metabolic challenge influences neuron function. In this study we have investigated the effects of anoxia, aglycemia, and acidosis upon intracellular Mg(2+) concentration [Mg(2+)](i) and intracellular pH (pH(i)) in isolated sensory neurons. Anoxia, anoxic aglycemia, and acidosis all caused a rise in [Mg(2+)](i) and a fall in pH(i). The rise in [Mg(2+)](i) in response to acidosis appears to be due to H(+) competing for intracellular Mg(2+) binding sites. The effects of anoxia and aglycemia were mimicked by metabolic inhibition and, in a dorsal root ganglia (DRG)-derived cell line, the rise in [Mg(2+)](i) during metabolic blockade was closely correlated with fall in intracellular ATP concentration ([ATP](i)). Increase in [Mg(2+)](i) during anoxia and aglycemia were therefore assumed to be due to MgATP hydrolysis. Even brief periods of anoxia (<3 min) resulted in rapid internal acidosis and a rise in [Mg(2+)](i) equivalent to a decline in MgATP levels of 15-20%. With more prolonged anoxia (20 min) MgATP depletion is estimated to be around 40%. With anoxic aglycemia, the [Mg(2+)](i) rise occurs in two phases: the first beginning almost immediately and the second after an 8- to 10-min delay. Within 20 min of anoxic aglycemia [Mg(2+)](i) was comparable to that observed following complete metabolic inhibition (dinitrophenol + 2-deoxyglucose, DNP + 2-DOG) indicating a near total loss of MgATP. The consequences of these events therefore need to be considered in the context of sensory neuron function in ischemia.
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Affiliation(s)
- Michael Henrich
- Department of Physiology, Anatomy and Genetics, Oxford OX1 3PT, United Kingdom
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Balfour RH, Trapp S. Ionic currents underlying the response of rat dorsal vagal neurones to hypoglycaemia and chemical anoxia. J Physiol 2007; 579:691-702. [PMID: 17218356 PMCID: PMC2151378 DOI: 10.1113/jphysiol.2006.126094] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
A proportion of dorsal vagal neurones (DVN) are glucosensors. These cells respond to brief hypoglycaemia either with a K(ATP) channel-mediated hyperpolarization or with depolarization owing to an as yet unknown mechanism. K(ATP) currents are observed not only during hypoglycaemia, but also in response to mitochondrial inhibition. Here we show that similarly to the observations for K(ATP) currents, both hypoglycaemia and inhibition of mitochondrial function elicited a small inward current that persisted in TTX in DVN of rat brainstem slices. Removal of glucose from the bath solution induced this inward current within 50 +/- 4 s in one subpopulation of DVN and in 279 +/- 36 s in another subpopulation. No such subpopulations were observed for the response to mitochondrial inhibition. Biophysical analysis revealed that mitochondrial inhibition or hypoglycaemia inhibited an openly rectifying K+ conductance in 25% of DVN. In the remaining cells, either an increase in conductance, with a reversal potential between -58 and +10 mV, or a parallel inward shift of the holding current was observed. This current most probably resulted from inhibition of the Na+-K+-ATPase and/or the opening of an ion channel. Recordings with electrodes containing 145 mm instead of 5 mm Cl- failed to shift the reversal potential of the inward current, indicating that a Cl- channel was not involved. In summary, glucosensing and non-glucosensing DVN appear to use common electrical pathways to respond to mitochondrial inhibition and to hypoglycaemia. We suggest that differences in glucose metabolism rather than differences in the complement of ion channels distinguish these two cell types.
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Affiliation(s)
- Robert H Balfour
- Department of Anaesthetics, Pain Medicine and Intensive Care, Chelsea & Westminster Hospital, Imperial College London, UK
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Kim JH, Kim JH, Kwon TH, Park YK, Chung HS. DPCPX-resistant hypoxic synaptic depression in the CA1 region of hippocampal slices: Possible role of intracellular accumulation of monocarboxylates. Neurosci Lett 2006; 403:141-6. [PMID: 16714083 DOI: 10.1016/j.neulet.2006.04.032] [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] [Received: 01/23/2006] [Revised: 04/17/2006] [Accepted: 04/21/2006] [Indexed: 10/24/2022]
Abstract
Adenosine plays the principal role in synaptic depression during various energy-depleted conditions. However, additional inhibitory factors not associated with A1 adenosine receptors appear to be involved in hypoxic insults. Monocarboxylate accumulation and consequent acidic changes during hypoxia may be responsible for this remaining depression in synaptic activity. Field evoked potentials were recorded in the CA1 region of rat hippocampal slices. Preincubation with 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) disclosed 43% of DPCPX-resistant synaptic depression (DRSD) during oxygen deprivation (OD). In contrast, no DRSD was detected in various conditions with limited glucose utilization, such as glucose deprivation and oxygen-glucose deprivation. Inhibition of anaerobic glycolysis (iodoacetate, sodium fluoride) abolished DRSD during OD, whereas blockade of monocarboxylate utilization with alpha-cyano-4-hydroxycinnamic acid (4-CIN) provoked DRSD in normoxic medium. These observations suggest that an intracellular accumulation of monocarboxylates is responsible for DRSD during hypoxia.
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Affiliation(s)
- Jong-Hyun Kim
- Department of Neurosurgery, Korea University Guro Hospital, 80 Guro-dong, Seoul 152-703, Republic of Korea
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Abstract
During severe arterial hypoxia leading to brain anoxia, most mammalian neurons undergo a massive depolarisation terminating in cell death. However, some neurons of the adult brain and most immature nervous structures tolerate extended periods of hypoxia-anoxia. An understanding of the mechanisms underlying this tolerance to oxygen depletion is pivotal for developing strategies to protect the brain from consequences of hypoxic-ischemic insults. ATP-sensitive K(+) (K(ATP)) channels are good subjects for this study as they are activated by processes associated with energy deprivation and can counteract the terminal anoxic-ischemic neuronal depolarisation. This review summarises in vitro analyses on the role of K(ATP) channels in hypoxia-anoxia in three distinct neuronal systems of rodents. In dorsal vagal neurons, blockade of K(ATP) channels with sulfonylureas abolishes the hypoxic-anoxic hyperpolarisation. However, this does not affect the extreme tolerance of these neurons to oxygen depletion as evidenced by a moderate and sustained increase of intracellular Ca(2+) (Ca(i)). By contrast, a sulfonylurea-induced block of K(ATP) channels shortens the delay of occurrence of a major Ca(i) rise in cerebellar Purkinje neurons. In neurons of the neonatal medullary respiratory network, K(ATP) channel blockers reverse the anoxic hyperpolarisation associated with slowing of respiratory frequency. This may constitute an adaptive mechanism for energy preservation. These studies demonstrate that K(ATP) channels are an ubiquituous feature of mammalian neurons and may, indeed, play a protective role in brain hypoxia.
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Affiliation(s)
- Klaus Ballanyi
- Department of Physiology & Pediatrics, Perinatal Research Centre, University of Alberta, 232 HMRC, Edmonton, Alberta, T6G 2S2, Canada.
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