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Lale N, Ditting T, Hilgers KF, Linz P, Ott C, Schmieder RE, Schiffer M, Amann K, Veelken R, Rodionova K. Afferent neurons of the kidney with impaired firing pattern in inflammation - role of sodium currents? Pflugers Arch 2023; 475:1329-1342. [PMID: 37672108 PMCID: PMC10567872 DOI: 10.1007/s00424-023-02852-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 08/15/2023] [Accepted: 08/16/2023] [Indexed: 09/07/2023]
Abstract
Peripheral neurons with renal afferents exhibit a predominantly tonic firing pattern of higher frequency that is reduced to low frequencies (phasic firing pattern) in renal inflammation. We wanted to test the hypothesis that the reduction in firing activity during inflammation is due to high-activity tonic neurons switching from higher to low frequencies depending on altered sodium currents. We identified and cultivated afferent sensory neurons with renal projections from the dorsal root ganglia (Th11-L2). Cultivated neurons were incubated with the chemokine CXCL1 (1,5 nmol/ml) for 12 h. We characterized neurons as "tonic," i.e., sustained action potential (AP) firing, or "phasic," i.e., < 5 APs upon stimulation in the current clamp. Their membrane currents were investigated in a voltage clamp. Data analyzed: renal vs. non-renal and tonic vs. phasic neurons. Renal afferent neurons exposed to CXCL1 showed a decrease in tonic firing pattern (CXCL1: 35,6% vs. control: 57%, P < 0.05). Na+ and K+ currents were not different between control renal and non-renal DRG neurons. Phasic neurons exhibited higher Na+ and K+ currents than tonic resulting in shorter APs (3.7 ± 0.3 vs. 6.1 ± 0.6 ms, P < 0.01). In neurons incubated with CXCL1, Na+ and K+ peak current density increased in phasic (Na+: - 969 ± 47 vs. - 758 ± 47 nA/pF, P < 0.01; K+: 707 ± 22 vs. 558 ± 31 nA/pF, P < 0.01), but were unchanged in tonic neurons. Phasic neurons exposed to CXCL1 showed a broader range of Na+ currents ([- 365- - 1429 nA] vs. [- 412- - 4273 nA]; P < 0.05) similar to tonic neurons. After CXCL1 exposure, significant changes in phasic neurons were observed in sodium activation/inactivation as well as a wider distribution of Na+ currents characteristic of tonic neurons. These findings indicate a subgroup of tonic neurons besides mere tonic or phasic neurons exists able to exhibit a phasic activity pattern under pathological conditions.
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Affiliation(s)
- Nena Lale
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
| | - Tilmann Ditting
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
- Department of Internal Medicine 4 - Nephrology and Hypertension, Paracelsus Private Medical School Nuremberg, Nuremberg, Germany
| | - Karl F Hilgers
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
| | - Peter Linz
- Department of Radiology, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
| | - Christian Ott
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
- Department of Internal Medicine 4 - Nephrology and Hypertension, Paracelsus Private Medical School Nuremberg, Nuremberg, Germany
| | - Roland E Schmieder
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
| | - Mario Schiffer
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
| | - Kerstin Amann
- Department of Nephropathology, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
| | - Roland Veelken
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany.
- Department of Internal Medicine 4 - Nephrology and Hypertension, Paracelsus Private Medical School Nuremberg, Nuremberg, Germany.
| | - Kristina Rodionova
- Department of Internal Medicine 4 Nephrology and Hypertension, Friedrich-Alexander University Erlangen, 91054, Erlangen, Germany
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Yang M, Li Y, Liu L, Zhou M. A novel proline-rich M-superfamily conotoxin that can simultaneously affect sodium, potassium and calcium currents. J Venom Anim Toxins Incl Trop Dis 2021; 27:e20200164. [PMID: 34234819 PMCID: PMC8230863 DOI: 10.1590/1678-9199-jvatitd-2020-0164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 03/01/2021] [Indexed: 12/19/2022] Open
Abstract
Background Conotoxins have become a research hotspot in the neuropharmacology field for their high activity and specificity in targeting ion channels and neurotransmitter receptors. There have been reports of a conotoxin acting on two ion channels, but rare reports of a conotoxin acting on three ion channels. Methods Vr3a, a proline-rich M-superfamily conotoxin from a worm-hunting Conus varius, was obtained by solid-phase synthesis and identified by mass spectrometry. The effects of synthesized Vr3a on sodium, potassium and calcium currents were tested on rat DRG cells by patch clamp experiments. The further effects of Vr3a on human Cav1.2 and Cav2.2 currents were tested on HEK293 cells. Results About 10 μM Vr3a has no effects on the peak sodium currents, but can induce a ~10 mV shift in a polarizing direction in the current-voltage relationship. In addition, 10 μM Vr3a can increase 19.61 ± 5.12% of the peak potassium currents and do not induce a shift in the current-voltage relationship. An amount of 10 μM Vr3a can inhibit 31.26% ± 4.53% of the peak calcium currents and do not induce a shift in the current-voltage relationship. The IC50 value of Vr3a on calcium channel currents in rat DRG neurons is 19.28 ± 4.32 μM. Moreover, 10 μM Vr3a can inhibit 15.32% ± 5.41% of the human Cav1.2 currents and 12.86% ± 4.93% of the human Cav2.2 currents. Conclusions Vr3a can simultaneously affect sodium, potassium and calcium currents. This novel triple-target conotoxin Vr3a expands understanding of conotoxin functions.
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Affiliation(s)
- Manyi Yang
- Department of Hepatobiliary and Pancreatic Surgery, NHC Key Laboratory of Nanobiological Technology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yubin Li
- Department of Oncology, State Local Joint Engineering Laboratory for Anticancer Drugs, NHC Key Laboratory of Cancer Proteomics, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Longfei Liu
- Department of Urology, National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Maojun Zhou
- Department of Oncology, State Local Joint Engineering Laboratory for Anticancer Drugs, NHC Key Laboratory of Cancer Proteomics, Xiangya Hospital, Central South University, Changsha, Hunan, China
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Sasaki T, Ikeda K, Nakajima T, Kawabata-Iwakawa R, Iizuka T, Dharmawan T, Tamura S, Niwamae N, Tange S, Nishiyama M, Kaneko Y, Kurabayashi M. Multiple arrhythmic and cardiomyopathic phenotypes associated with an SCN5A A735E mutation. J Electrocardiol 2021; 65:122-127. [PMID: 33610078 DOI: 10.1016/j.jelectrocard.2021.01.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 01/29/2021] [Accepted: 01/29/2021] [Indexed: 12/19/2022]
Abstract
BACKGROUND SCN5A mutations are associated with multiple arrhythmic and cardiomyopathic phenotypes including Brugada syndrome (BrS), sinus node dysfunction (SND), atrioventricular block, supraventricular tachyarrhythmias (SVTs), long QT syndrome (LQTS), dilated cardiomyopathy and left ventricular noncompaction. Several single SCN5A mutations have been associated with overlap of some of these phenotypes, but never with overlap of all the phenotypes. OBJECTIVE We encountered two pedigrees with multiple arrhythmic phenotypes with or without cardiomyopathic phenotypes, and sought to identify a responsible mutation and reveal its functional abnormalities. METHODS Target panel sequencing of 72 genes, including inherited arrhythmia syndromes- and cardiomyopathies-related genes, was employed in two probands. Cascade screening was performed by Saner sequencing. Wild-type or identified mutant SCN5A were expressed in tsA201 cells, and whole-cell sodium currents (INa) were recorded using patch-clamp techniques. RESULTS We identified an SCN5A A735E mutation in these probands, but did not identify any other mutations. All eight mutation carriers exhibited at least one of the arrhythmic phenotypes. Two patients exhibited multiple arrhythmic phenotypes: one (15-year-old girl) exhibited BrS, SND, and exercise and epinephrine-induced QT prolongation, the other (4-year-old boy) exhibited BrS, SND, and SVTs. Another one (30-year-old male) exhibited all arrhythmic and cardiomyopathic phenotypes, except for LQTS. One male suddenly died at age 22. Functional analysis revealed that the mutant did not produce functional INa. CONCLUSIONS A non-functional SCN5A A735E mutation could be associated with multiple arrhythmic and cardiomyopathic phenotypes, although there remains a possibility that other unidentified factors may be involved in the phenotypic variability of the mutation carriers.
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Affiliation(s)
- Takashi Sasaki
- Department of Cardiovascular Medicine, Japanese Red Cross Maebashi Hospital, Maebashi, Gunma, Japan
| | - Kentaro Ikeda
- Department of Cardiology, Gunma Children's Medical Center, Shibukawa, Gunma, Japan
| | - Tadashi Nakajima
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
| | - Reika Kawabata-Iwakawa
- Division of Integrated Oncology Research, Gunma University Initiative for Advanced Research, Maebashi, Gunma, Japan
| | - Takashi Iizuka
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Tommy Dharmawan
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Shuntaro Tamura
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Nogiku Niwamae
- Department of Cardiovascular Medicine, Japanese Red Cross Maebashi Hospital, Maebashi, Gunma, Japan
| | - Shoichi Tange
- Department of Cardiovascular Medicine, Japanese Red Cross Maebashi Hospital, Maebashi, Gunma, Japan
| | | | - Yoshiaki Kaneko
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Masahiko Kurabayashi
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
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Dharmawan T, Nakajima T, Iizuka T, Tamura S, Matsui H, Kaneko Y, Kurabayashi M. Enhanced closed-state inactivation of mutant cardiac sodium channels (SCN5A N1541D and R1632C) through different mechanisms. J Mol Cell Cardiol 2019; 130:88-95. [PMID: 30935997 DOI: 10.1016/j.yjmcc.2019.03.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 03/27/2019] [Accepted: 03/29/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND SCN5A variants can be associated with overlapping phenotypes such as Brugada syndrome (BrS), sinus node dysfunction and supraventricular tachyarrhythmias. Our genetic screening of SCN5A in 65 consecutive BrS probands revealed two patients with overlapping phenotypes: one carried an SCN5A R1632C (in domain IV-segment 4), which we have previously reported, the other carried a novel SCN5A N1541D (in domain IV-segment 1). OBJECTIVE We sought to reveal whether or not these variants are associated with the same biophysical defects. METHODS Wild-type (WT) or mutant SCN5A was expressed in tsA201-cells, and whole-cell sodium currents (hNav1.5/INa) were recorded using patch-clamp techniques. RESULTS The N1541D-INa density, when assessed from a holding potential of -150 mV, was not different from WT-INa as with R1632C-INa, indicating that SCN5A N1541D did not cause trafficking defects. The steady-state inactivation curve of N1541D-INa was markedly shifted to hyperpolarizing potentials in comparison to WT-INa (V1/2-WT: -82.3 ± 0.9 mV, n = 15; N1541D: -108.8 ± 1.6 mV, n = 26, P < .01) as with R1632C-INa. Closed-state inactivation (CSI) was evaluated using prepulses of -90 mV for 1460 ms. Residual N1541D-INa and R1632C-INa were markedly reduced in comparison to WT-INa (WT: 63.8 ± 4.6%, n = 18; N1541D: 15.1 ± 2.3%, n = 19, P < .01 vs WT; R1632C: 5.3 ± 0.5%, n = 15, P < .01 vs WT). Entry into CSI of N1541D-INa was markedly accelerated, and that of R1632C-INa was weakly accelerated in comparison to WT-INa (tau-WT: 65.8 ± 7.4 ms, n = 18; N1541D: 13.7 ± 1.1 ms, n = 19, P < .01 vs WT; R1632C: 39.5 ± 2.9 ms, n = 15, P < .01 vs WT and N1541D). Although N1541D-INa recovered from closed-state fast inactivation at the same rate as WT-INa, R1632C-INa recovered very slowly (tau-WT: 1.90 ± 0.16 ms, n = 10; N1541D: 1.72 ± 0.12 ms, n = 10, P = .41 vs WT; R1632C: 53.0 ± 2.5 ms, n = 14, P < .01 vs WT and N1541D). CONCLUSIONS Both N1541D-INa and R1632C-INa exhibited marked enhancement of CSI, but through different mechanisms. The data provided a novel understanding of the mechanisms of CSI of INa. Clinically, the enhanced CSI of N1541D-INa leads to a severe loss-of-function of INa at voltages near the physiological resting membrane potential (~-90 mV) of cardiac myocytes; this can be attributable to the patient's phenotypic manifestations.
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Affiliation(s)
- Tommy Dharmawan
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Tadashi Nakajima
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
| | - Takashi Iizuka
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Shuntaro Tamura
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Hiroki Matsui
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, Maebashi, Gunma, Japan
| | - Yoshiaki Kaneko
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Masahiko Kurabayashi
- Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
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Abstract
Endothelin-1 (ET-1) has been demonstrated to be a pro-nociceptive as well as an anti-nociceptive agent. However, underlying molecular mechanisms for these pain modulatory actions remain unclear. In the present study, we evaluated the ability of ET-1 to alter the nociceptor excitability using a patch clamp technique in acutely dissociated rat dorsal root ganglion (DRG) neurons. ET-1 produced an increase in threshold current to evoke an action potential (I threshold) and hyperpolarization of resting membrane potential (RMP) indicating decreased excitability of DRG neurons. I threshold increased from 0.25 ± 0.08 to 0.33 ± 0.07 nA and hyperpolarized RMP from -57.51 ± 1.70 to -67.41 ± 2.92 mV by ET-1 (100 nM). The hyperpolarizing effect of ET-1 appears to be orchestrated via modulation of membrane conductances, namely voltage-gated sodium current (I Na) and outward transient potassium current (I KT). ET-1, 30 and 100 nM, decreased the peak I Na by 41.3 ± 6.8 and 74 ± 15.2%, respectively. Additionally, ET-1 (100 nM) significantly potentiated the transient component (I KT) of the potassium currents. ET-1-induced effects were largely attenuated by BQ-788, a selective ETBR blocker. However, a selective ETAR blocker BQ-123 did not alter the effects of ET-1. A selective ETBR agonist, IRL-1620, mimicked the effect of ET-1 on I Na in a concentration-dependent manner (IC50 159.5 ± 92.6 μM). In conclusion, our results demonstrate that ET-1 hyperpolarizes nociceptors by blocking I Na and potentiating I KT through selective activation of ETBR, which may represent one of the underlying mechanisms for reported anti-nociceptive effects of ET-1.
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Affiliation(s)
- Nandkishor K Mule
- Electrophysiology Laboratory, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab, 160062, India
| | - Jitendra N Singh
- Electrophysiology Laboratory, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab, 160062, India.
| | - Kunal U Shah
- Electrophysiology Laboratory, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab, 160062, India
| | - Anil Gulati
- Department of Pharmaceutical Sciences, Chicago College of Pharmacy, Midwestern University, Downers Grove, IL, 60515, USA
| | - Shyam S Sharma
- Electrophysiology Laboratory, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab, 160062, India.
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Nakajima T, Kaneko Y, Saito A, Ota M, Iijima T, Kurabayashi M. Enhanced fast-inactivated state stability of cardiac sodium channels by a novel voltage sensor SCN5A mutation, R1632C, as a cause of atypical Brugada syndrome. Heart Rhythm 2015; 12:2296-304. [PMID: 26031372 DOI: 10.1016/j.hrthm.2015.05.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Indexed: 12/19/2022]
Abstract
BACKGROUND Mutations in SCN5A, which encodes the cardiac voltage-gated sodium channels, can be associated with multiple electrophysiological phenotypes. A novel SCN5A R1632C mutation, located in the domain IV-segment 4 voltage sensor, was identified in a young male patient who had a syncopal episode during exercise and presented with atrial tachycardia, sinus node dysfunction, and Brugada syndrome. OBJECTIVE We sought to elucidate the functional consequences of the R1632C mutation. METHODS The wild-type (WT) or R1632C SCN5A mutation was coexpressed with β1 subunit in tsA201 cells, and whole-cell sodium currents (INa) were recorded using patch-clamp methods. RESULTS INa density, measured at -20 mV from a holding potential of -120 mV, for R1632C was significantly lower than that for WT (R1632C: -433 ± 52 pA/pF, n = 14; WT: -672 ± 90 pA/pF, n = 15; P < .05); however, no significant changes were observed in the steady-state activation and fast inactivation rate. The steady-state inactivation curve for R1632C was remarkably shifted to hyperpolarizing potentials compared with that for WT (R1632C: V1/2 = -110.7 ± 0.8 mV, n = 16; WT: V1/2 = -85.9 ± 2.5 mV, n = 17; P < .01). The steady-state fast inactivation curve for R1632C was also shifted to the same degree. Recovery from fast inactivation after a 20-ms depolarizing pulse for R1632C was remarkably delayed compared with that for WT (R1632C: τ = 246.7 ± 14.3 ms, n = 8; WT: τ = 3.7 ± 0.3 ms, n = 8; P < .01). Repetitive depolarizing pulses at various cycle lengths greatly attenuated INa for R1632C than that for WT. CONCLUSION R1632C showed a loss of function of INa by an enhanced fast-inactivated state stability because of a pronounced impairment of recovery from fast inactivation, which may explain the phenotypic manifestation observed in our patient.
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Affiliation(s)
- Tadashi Nakajima
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan.
| | - Yoshiaki Kaneko
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Akihiro Saito
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Masaki Ota
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Takafumi Iijima
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Masahiko Kurabayashi
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan
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