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Liu H, Dai H, Qiu F, Chen Y, Liang CL, Yang B, Gong N, Bromberg JS, Dai Z. Electrostimulation suppresses allograft rejection via promoting lymphatic regulatory T cell migration mediated by lymphotoxin - lymphotoxin receptor β signaling. Am J Transplant 2024:S1600-6135(24)00392-7. [PMID: 38992495 DOI: 10.1016/j.ajt.2024.06.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 06/21/2024] [Accepted: 06/25/2024] [Indexed: 07/13/2024]
Abstract
Conventional immunosuppressants that suppress allograft rejection cause various side effects. Although regulatory T cells (Tregs) are essential for allograft survival, the limited efficacy of Treg therapy demands improvement. Thus, it is imperative to seek new approaches to enhancing Treg suppression. Low-intensity electrostimulation (ES) has been shown to exert antiinflammatory effects without causing major adverse reactions. However, it remains unknown whether and how ES regulates alloimmunity. Here, we found that regional ES delayed murine skin allograft rejection and promoted long-term allograft survival induced by an mTOR inhibitor, rapamycin. ES also extended islet allograft survival. Mechanistically, ES enhanced the expression of lymphotoxin α (LTα) on Tregs after transplantation. Blockade of lymphotoxin β receptor-mediated nonclassical NFκB signaling suppressed lymphatic Treg migration and largely reversed the effects of ES on allograft survival. Moreover, ES failed to extend allograft survival when recipients lacked LTα/lymph nodes or if transferred Tregs lacked LTα. Therefore, ES promoted the lymphatic migration of CD4+Foxp3+ Tregs by upregulating their surface expression of LTα. Finally, ES augmented expression of LTα on murine or human Tregs, but not conventional T cells, while promoting their calcium influx in vitro. This ES-mediated upregulation of LTα relied on calcium influx. Thus, our findings have unveiled novel mechanisms underlying ES-mediated immunoregulation.
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Affiliation(s)
- Huazhen Liu
- Section of Immunology, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China; State Key Laboratory of Traditional Chinese Medicine Syndrome, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China
| | - Helong Dai
- Department of Kidney Transplantation, Center of Organ Transplantation, the Second Xiangya Hospital of Central South University, Changsha, China
| | - Feifei Qiu
- Section of Immunology, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China
| | - Yuchao Chen
- Section of Immunology, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China; State Key Laboratory of Dampness Syndrome of Chinese Medicine, Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China
| | - Chun-Ling Liang
- Section of Immunology, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China; State Key Laboratory of Dampness Syndrome of Chinese Medicine, Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China
| | - Bin Yang
- Department of Cardiovascular Sciences, College of Life Sciences University of Leicester, Leicester, UK
| | - Nianqiao Gong
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Key Laboratory of Organ Transplantation of Ministry of Education, National Health Commission and Chinese Academy of Medical Sciences, Wuhan, Hubei, China.
| | - Jonathan S Bromberg
- Kidney and Pancreas Transplantation, Department of Surgery and Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA.
| | - Zhenhua Dai
- Section of Immunology, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China; State Key Laboratory of Dampness Syndrome of Chinese Medicine, Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China.
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Yun SH, Mansurov V, Yang L, Yoon J, Leblanc N, Craviso GL, Zaklit J. Modulating Ca 2+ influx into adrenal chromaffin cells with short-duration nanosecond electric pulses. Biophys J 2024:S0006-3495(24)00418-1. [PMID: 38909279 DOI: 10.1016/j.bpj.2024.06.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 05/07/2024] [Accepted: 06/20/2024] [Indexed: 06/24/2024] Open
Abstract
Isolated bovine adrenal chromaffin cells exposed to single 2-, 4-, or 5-ns pulses undergo a rapid, transient rise in intracellular Ca2+ mediated by Ca2+ entry via voltage-gated Ca2+ channels (VGCCs), mimicking the activation of these cells in vivo by acetylcholine. However, pulse durations 150 ns or longer elicit larger amplitude and longer-lived Ca2+ responses due to Ca2+ influx via both VGCCs and a yet to be identified plasma membrane pathway(s). To further our understanding of the differential effects of ultrashort versus longer pulse durations on Ca2+ influx, chromaffin cells were loaded with calcium green-1 and exposed to single 3-, 5-, 11-, 25-, or 50-ns pulses applied at their respective Ca2+ activation threshold electric fields. Increasing pulse duration from 3 or 5 ns to only 11 ns was sufficient to elicit increased amplitude and longer-lived Ca2+ responses in the majority of cells, a trend that continued as pulse duration increased to 50 ns. The amplification of Ca2+ responses was not the result of Ca2+ release from intracellular stores and was accompanied by a decreased effectiveness of VGCC inhibitors to block the responses and a reduced reliance on extracellular Na+ and membrane depolarization to evoke the responses. Inhibitors of pannexin channels, P2X receptors, or non-selective cation channels failed to attenuate 50-ns-elicited Ca2+ responses, ruling out these Ca2+-permeable channels as secondary Ca2+ entry pathways. Analytical calculations and numerical modeling suggest that the parameter that best determines the response of chromaffin cells to increasing pulse durations is the time the membrane charges to its peak voltage. These results highlight the pronounced sensitivity of a neuroendocrine cell to pulse durations differing by only tens of nanoseconds, which has important implications for the future development of nanosecond pulse technologies enabling electrostimulation applications for spatially focused and graded in vivo neuromodulation.
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Affiliation(s)
- Sung Hae Yun
- Department of Electrical and Biomedical Engineering, College of Engineering, University of Nevada, Reno, Nevada
| | - Vasilii Mansurov
- Department of Electrical and Biomedical Engineering, College of Engineering, University of Nevada, Reno, Nevada
| | - Lisha Yang
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Jihwan Yoon
- Department of Electrical and Biomedical Engineering, College of Engineering, University of Nevada, Reno, Nevada
| | - Normand Leblanc
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Gale L Craviso
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Josette Zaklit
- Department of Electrical and Biomedical Engineering, College of Engineering, University of Nevada, Reno, Nevada.
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Kim V, Semenov I, Kiester AS, Keppler MA, Ibey BL, Bixler JN, Colunga Biancatelli RML, Pakhomov AG. Control of the Electroporation Efficiency of Nanosecond Pulses by Swinging the Electric Field Vector Direction. Int J Mol Sci 2023; 24:10921. [PMID: 37446096 PMCID: PMC10341945 DOI: 10.3390/ijms241310921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 06/27/2023] [Accepted: 06/28/2023] [Indexed: 07/15/2023] Open
Abstract
Reversing the pulse polarity, i.e., changing the electric field direction by 180°, inhibits electroporation and electrostimulation by nanosecond electric pulses (nsEPs). This feature, known as "bipolar cancellation," enables selective remote targeting with nsEPs and reduces the neuromuscular side effects of ablation therapies. We analyzed the biophysical mechanisms and measured how cancellation weakens and is replaced by facilitation when nsEPs are applied from different directions at angles from 0 to 180°. Monolayers of endothelial cells were electroporated by a train of five pulses (600 ns) or five paired pulses (600 + 600 ns) applied at 1 Hz or 833 kHz. Reversing the electric field in the pairs (180° direction change) caused 2-fold (1 Hz) or 20-fold (833 kHz) weaker electroporation than the train of single nsEPs. Reducing the angle between pulse directions in the pairs weakened cancellation and replaced it with facilitation at angles <160° (1 Hz) and <130° (833 kHz). Facilitation plateaued at about three-fold stronger electroporation compared to single pulses at 90-100° angle for both nsEP frequencies. The profound dependence of the efficiency on the angle enables novel protocols for highly selective focal electroporation at one electrode in a three-electrode array while avoiding effects at the other electrodes. Nanosecond-resolution imaging of cell membrane potential was used to link the selectivity to charging kinetics by co- and counter-directional nsEPs.
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Affiliation(s)
- Vitalii Kim
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA
| | - Iurii Semenov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA
| | - Allen S. Kiester
- Bioeffects Division, Airman System Directorate, 711th Human Performance Wing, Air Force Research Laboratory, JBSA Fort Sam Houston, San Antonio, TX 78234, USA
| | | | - Bennett L. Ibey
- Bioeffects Division, Airman System Directorate, 711th Human Performance Wing, Air Force Research Laboratory, JBSA Fort Sam Houston, San Antonio, TX 78234, USA
| | - Joel N. Bixler
- Bioeffects Division, Airman System Directorate, 711th Human Performance Wing, Air Force Research Laboratory, JBSA Fort Sam Houston, San Antonio, TX 78234, USA
| | - Ruben M. L. Colunga Biancatelli
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23508, USA
| | - Andrei G. Pakhomov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA
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Ibrahimi N, Vallet L, Andre FM, Rivaletto M, Novac BM, Mir LM, Pécastaing L. An Overview of Subnanosecond Pulsed Electric Field Biological Effects: Toward Contactless Technologies for Cancer Treatment. Bioelectricity 2023. [DOI: 10.1089/bioe.2022.0031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023] Open
Affiliation(s)
- Njomza Ibrahimi
- Laboratoire des Sciences de l'Ingénieur Appliquées à la Mécanique et au Génie Électrique–Fédération IPRA, EA4581, Université de Pau et des Pays de l'Adour/E2S UPPA, Pau, France
| | - Leslie Vallet
- Université Paris-Saclay, CNRS, Gustave Roussy, UMR 9018, Metabolic and Systemic Aspects of Oncogenesis (METSY), Villejuif, France
| | - Franck M. Andre
- Université Paris-Saclay, CNRS, Gustave Roussy, UMR 9018, Metabolic and Systemic Aspects of Oncogenesis (METSY), Villejuif, France
| | - Marc Rivaletto
- Laboratoire des Sciences de l'Ingénieur Appliquées à la Mécanique et au Génie Électrique–Fédération IPRA, EA4581, Université de Pau et des Pays de l'Adour/E2S UPPA, Pau, France
| | - Bucur M. Novac
- Laboratoire des Sciences de l'Ingénieur Appliquées à la Mécanique et au Génie Électrique–Fédération IPRA, EA4581, Université de Pau et des Pays de l'Adour/E2S UPPA, Pau, France
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough, United Kingdom
| | - Lluis M. Mir
- Université Paris-Saclay, CNRS, Gustave Roussy, UMR 9018, Metabolic and Systemic Aspects of Oncogenesis (METSY), Villejuif, France
| | - Laurent Pécastaing
- Laboratoire des Sciences de l'Ingénieur Appliquées à la Mécanique et au Génie Électrique–Fédération IPRA, EA4581, Université de Pau et des Pays de l'Adour/E2S UPPA, Pau, France
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Kim V, Semenov I, Kiester AS, Keppler MA, Ibey BL, Bixler JN, Pakhomov AG. Action spectra and mechanisms of (in) efficiency of bipolar electric pulses at electroporation. Bioelectrochemistry 2023; 149:108319. [PMID: 36375440 PMCID: PMC9729435 DOI: 10.1016/j.bioelechem.2022.108319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 10/19/2022] [Accepted: 11/04/2022] [Indexed: 11/09/2022]
Abstract
The reversal of the electric field direction inhibits various biological effects of nanosecond electric pulses (nsEP). This feature, known as "bipolar cancellation," enables interference targeting of nsEP bioeffects remotely from stimulating electrodes, for prospective applications such as precise cancer ablation and non-invasive deep brain stimulation. This study was undertaken to achieve the maximum cancellation of electroporation, by quantifying the impact of the pulse shape, duration, number, and repetition rate across a broad range of electric field strengths. Monolayers of endothelial cells (BPAE) were electroporated in a non-uniform electric field. Cell membrane permeabilization was quantified by YO-PRO-1 (YP) dye uptake and correlated to local electric field strength. For most conditions tested, adding an opposite polarity phase reduced YP uptake by 50-80 %. The strongest cancellation, which reduced YP uptake by 95-97 %, was accomplished by adding a 50 % second phase to 600-ns pulses delivered at a high repetition rate of 833 kHz. Strobe photography of nanosecond kinetics of membrane potential in single CHO cells revealed the temporal summation of polarization by individual unipolar nsEP applied at sub-MHz rate, leading to enhanced electroporation. In contrast, there was no summation for bipolar pulses, and increasing their repetition rate suppressed electroporation. These new findings are discussed in the context of bipolar cancellation mechanisms and remote focusing applications.
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Affiliation(s)
- Vitalii Kim
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA
| | - Iurii Semenov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA
| | - Allen S Kiester
- Bioeffects Division, Airman System Directorate, 711th Human Performance Wing, Air Force Research Laboratory, JBSA Fort Sam Houston, TX, USA
| | | | - Bennett L Ibey
- Bioeffects Division, Airman System Directorate, 711th Human Performance Wing, Air Force Research Laboratory, JBSA Fort Sam Houston, TX, USA
| | - Joel N Bixler
- Bioeffects Division, Airman System Directorate, 711th Human Performance Wing, Air Force Research Laboratory, JBSA Fort Sam Houston, TX, USA
| | - Andrei G Pakhomov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA.
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Silkunas M, Gudvangen E, Novickij V, Pakhomov AG. Sub-MHz bursts of nanosecond pulses excite neurons at paradoxically low electric field thresholds without membrane damage. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184034. [PMID: 35981654 DOI: 10.1016/j.bbamem.2022.184034] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/29/2022] [Accepted: 08/08/2022] [Indexed: 06/15/2023]
Abstract
Neuromodulation applications of nanosecond electric pulses (nsEP) are hindered by their low potency to elicit action potentials in neurons. Excitation by a single nsEP requires a strong electric field which injures neurons by electroporation. We bypassed the high electric field requirement by replacing single nsEP stimuli with high-frequency brief nsEP bursts. In hippocampal neurons, excitation thresholds progressively decreased at nsEP frequencies above 20-200 kHz, with up to 20-30-fold reduction at sub-MHz and MHz rates. For a fixed burst duration, thresholds were determined by the duty cycle, irrespective of the specific nsEP duration, rate, or number of pulses per burst. For 100-μs bursts of 100-, 400-, or 800-ns pulses, the threshold decreased as a power function when the duty cycle exceeded 3-5 %. nsEP bursts were compared with single "long" pulses whose duration and amplitude matched the duration and the time-average amplitude of the burst. Such pulses deliver the same electric charge as bursts, within the same time interval. High-frequency nsEP bursts excited neurons at the time-average electric field 2-3 times below the threshold for a single long pulse. For example, the excitation threshold of 139 ± 14 V/cm for a single 100-μs pulse decreased to 57 ± 8 V/cm for a 100-μs burst of 100-ns, 0.25-MHz pulses (p < 0.001). Applying nsEP in bursts reduced or prevented the loss of excitability in multiple stimulation attempts. Stimulation by high-frequency nsEP bursts is a powerful novel approach to excite neurons at paradoxically low electric charge while also avoiding the electroporative membrane damage.
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Affiliation(s)
- Mantas Silkunas
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA; Institute for Digestive System Research, Lithuanian University of Health Sciences, 44307 Kaunas, Lithuania
| | - Emily Gudvangen
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA
| | | | - Andrei G Pakhomov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA.
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Electroporation and cell killing by milli- to nanosecond pulses and avoiding neuromuscular stimulation in cancer ablation. Sci Rep 2022; 12:1763. [PMID: 35110567 PMCID: PMC8811018 DOI: 10.1038/s41598-022-04868-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 12/31/2021] [Indexed: 12/21/2022] Open
Abstract
Ablation therapies aim at eradication of tumors with minimal impact on surrounding healthy tissues. Conventional pulsed electric field (PEF) treatments cause pain and muscle contractions far beyond the ablation area. The ongoing quest is to identify PEF parameters efficient at ablation but not at stimulation. We measured electroporation and cell killing thresholds for 150 ns–1 ms PEF, uni- and bipolar, delivered in 10- to 300-pulse trains at up to 1 MHz rates. Monolayers of murine colon carcinoma cells exposed to PEF were stained with YO-PRO-1 dye to detect electroporation. In 2–4 h, dead cells were labeled with propidium. Electroporation and cell death thresholds determined by matching the stained areas to the electric field intensity were compared to nerve excitation thresholds (Kim et al. in Int J Mol Sci 22(13):7051, 2021). The minimum fourfold ratio of cell killing and stimulation thresholds was achieved with bipolar nanosecond PEF (nsPEF), a sheer benefit over a 500-fold ratio for conventional 100-µs PEF. Increasing the bipolar nsPEF frequency up to 100 kHz within 10-pulse bursts increased ablation thresholds by < 20%. Restricting such bursts to the refractory period after nerve excitation will minimize the number of neuromuscular reactions while maintaining the ablation efficiency and avoiding heating.
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Kim V, Gudvangen E, Kondratiev O, Redondo L, Xiao S, Pakhomov AG. Peculiarities of Neurostimulation by Intense Nanosecond Pulsed Electric Fields: How to Avoid Firing in Peripheral Nerve Fibers. Int J Mol Sci 2021; 22:ijms22137051. [PMID: 34208945 PMCID: PMC8269031 DOI: 10.3390/ijms22137051] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 12/31/2022] Open
Abstract
Intense pulsed electric fields (PEF) are a novel modality for the efficient and targeted ablation of tumors by electroporation. The major adverse side effects of PEF therapies are strong involuntary muscle contractions and pain. Nanosecond-range PEF (nsPEF) are less efficient at neurostimulation and can be employed to minimize such side effects. We quantified the impact of the electrode configuration, PEF strength (up to 20 kV/cm), repetition rate (up to 3 MHz), bi- and triphasic pulse shapes, and pulse duration (down to 10 ns) on eliciting compound action potentials (CAPs) in nerve fibers. The excitation thresholds for single unipolar but not bipolar stimuli followed the classic strength–duration dependence. The addition of the opposite polarity phase for nsPEF increased the excitation threshold, with symmetrical bipolar nsPEF being the least efficient. Stimulation by nsPEF bursts decreased the excitation threshold as a power function above a critical duty cycle of 0.1%. The threshold reduction was much weaker for symmetrical bipolar nsPEF. Supramaximal stimulation by high-rate nsPEF bursts elicited only a single CAP as long as the burst duration did not exceed the nerve refractory period. Such brief bursts of bipolar nsPEF could be the best choice to minimize neuromuscular stimulation in ablation therapies.
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Affiliation(s)
- Vitalii Kim
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA; (V.K.); (E.G.); (S.X.)
| | - Emily Gudvangen
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA; (V.K.); (E.G.); (S.X.)
| | | | - Luis Redondo
- Lisbon Engineering Superior Institute, GIAAPP/ISEL, 1959-007 Lisbon, Portugal;
| | - Shu Xiao
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA; (V.K.); (E.G.); (S.X.)
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA 23508, USA
| | - Andrei G. Pakhomov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA; (V.K.); (E.G.); (S.X.)
- Correspondence:
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Sözer EB, Pakhomov AG, Semenov I, Casciola M, Kim V, Vernier PT, Zemlin CW. Analysis of electrostimulation and electroporation by high repetition rate bursts of nanosecond stimuli. Bioelectrochemistry 2021; 140:107811. [PMID: 33862549 DOI: 10.1016/j.bioelechem.2021.107811] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 03/26/2021] [Accepted: 03/28/2021] [Indexed: 12/16/2022]
Abstract
Exposures to short-duration, strong electric field pulses have been utilized for stimulation, ablation, and the delivery of molecules into cells. Ultrashort, nanosecond duration pulses have shown unique benefits, but they require higher field strengths. One way to overcome this requirement is to use trains of nanosecond pulses with high repetition rates, up to the MHz range. Here we present a theoretical model to describe the effects of pulse trains on the plasma membrane and intracellular membranes modeled as resistively charged capacitors. We derive the induced membrane potential and the stimulation threshold as functions of pulse number, pulse duration, and repetition rate. This derivation provides a straightforward method to calculate the membrane charging time constant from experimental data. The derived excitation threshold agrees with nerve stimulation experiments, indicating that nanosecond pulses are not more effective than longer pulses in charging nerve fibers. The derived excitation threshold does not, however, correctly predict the nanosecond stimulation of cardiomyocytes. We show that a better agreement is possible if multiple charging time constants are considered. Finally, we expand the model to intracellular membranes and show that pulse trains do not lead to charge buildup, but can create significant oscillations of the intracellular membrane potential.
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Affiliation(s)
- Esin B Sözer
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA.
| | - Andrei G Pakhomov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA
| | - Iurii Semenov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA
| | - Maura Casciola
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA
| | - Vitalii Kim
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA
| | - P Thomas Vernier
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA
| | - Christian W Zemlin
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA.
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