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Alom F, Matsuyama H, Nagano H, Fujikawa S, Tanahashi Y, Unno T. Involvement of transient receptor potential melastatin 4 channels in the resting membrane potential setting and cholinergic contractile responses in mouse detrusor and ileal smooth muscles. J Vet Med Sci 2019; 81:217-228. [PMID: 30518701 PMCID: PMC6395210 DOI: 10.1292/jvms.18-0631] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Here, we investigated the effects of 9-hydroxyphenanthrene (9-phenanthrol), a potent and selective transient receptor potential melastatin 4 (TRPM4) channel blocker, on the resting membrane potential and cholinergic contractile responses to elucidate the functional role of TRPM4 channels in the contractile activities of mouse detrusor and ileal longitudinal smooth muscles. We observed that, 9-phenanthrol (3-30 µM) did not significantly inhibit high K+-induced contractions in both preparations; however, 9-phenanthrol (10 µM) strongly inhibited cholinergic contractions evoked by electrical field stimulation in detrusor preparations compared to inhibitions in ileal preparations. 9-Phenanthrol (10 µM) significantly inhibited the muscarinic agonist, carbachol-induced contractile responses and slowed the maximum upstroke velocities of the contraction in detrusor preparations. However, the agent (10 µM) did not inhibit the contractions due to intracellular Ca2+ release evoked by carbachol, suggesting that the inhibitory effect of 9-phenanthrol may primarily be due to the inhibition of the membrane depolarization process incurred by TRPM4 channels. On the other hand, 9-phenanthrol (10 µM) did not affect carbachol-induced contractile responses in ileal preparations. Further, 9-phenanthrol (10 µM) significantly hyperpolarized the resting membrane potential and decreased the basal tone in both detrusor and ileal muscle preparations. Taken together, our results suggest that TRPM4 channels are constitutively active and are involved in setting of the resting membrane potential, thereby regulating the basal tone in detrusor and ileal smooth muscles. Thus, TRPM4 channels play a significant role in cholinergic signaling in detrusor, but not ileal, smooth muscles.
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Affiliation(s)
- Firoj Alom
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Hayato Matsuyama
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.,Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Hiroshi Nagano
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Saki Fujikawa
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Yasuyuki Tanahashi
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Toshihiro Unno
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.,Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
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Qiao S, Stieglitz T, Yoshida K. Estimation of the Electrode-Fiber Bioelectrical Coupling From Extracellularly Recorded Single Fiber Action Potentials. IEEE Trans Neural Syst Rehabil Eng 2015; 24:951-960. [PMID: 26469339 DOI: 10.1109/tnsre.2015.2489924] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Selective peripheral neural interfaces are currently capable of detecting minute electrical signals from nearby nerve fibers as single fiber action potential (SFAP) waveforms. Each detected single unit has a distinct shape originating from the unique bioelectrical coupling that exists between the neuroprosthetic electrode, the nerve fiber and the extracellular milieu. The bioelectrical coupling manifests itself as a series of low-pass Bessel filters acting on the action currents along the nerve fiber. Here, we present a method to estimate the electrode-fiber bioelectrical coupling through a quantitative analysis of the spectral distribution of the single units extracellularly recorded with the thin-film longitudinal intrafascicular electrode (tfLIFE) in an in vivo mammalian peripheral nerve animal model. The bioelectrical coupling estimate is an estimate of the electrode sensitivity function traversed by the nerve fiber, suggesting that it is as a means to directly measure the spatial relationship between the nerve fiber and electrode. It not only reflects a shape change to the SFAP, but has implications for in situ nerve fiber location tracking, in situ diagnostics of nerves and neuroproshetic electrodes, and assessment of the biocompatibility of neural interfaces and the health of the reporting nerve fibers.
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