Spatial Analysis of Slowly Oscillating Electric Activity in the Gut of Mice Using Low Impedance Arrayed Microelectrodes

Abstract

Smooth and elaborate gut motility is based on cellular cooperation, including smooth muscle, enteric neurons and special interstitial cells acting as pacemaker cells. Therefore, spatial characterization of electric activity in tissues containing these electric excitable cells is required for a precise understanding of gut motility. Furthermore, tools to evaluate spatial electric activity in a small area would be useful for the investigation of model animals. We thus employed a microelectrode array (MEA) system to simultaneously measure a set of 8×8 field potentials in a square area of ∼1 mm2. The size of each recording electrode was 50×50 µm2, however the surface area was increased by fixing platinum black particles. The impedance of microelectrode was sufficiently low to apply a high-pass filter of 0.1 Hz. Mapping of spectral power, and auto-correlation and cross-correlation parameters characterized the spatial properties of spontaneous electric activity in the ileum of wild-type (WT) and W/Wv mice, the latter serving as a model of impaired network of pacemaking interstitial cells. Namely, electric activities measured varied in both size and cooperativity in W/Wv mice, despite the small area. In the ileum of WT mice, procedures suppressing the excitability of smooth muscle and neurons altered the propagation of spontaneous electric activity, but had little change in the period of oscillations. In conclusion, MEA with low impedance electrodes enables to measure slowly oscillating electric activity, and is useful to evaluate both histological and functional changes in the spatio-temporal property of gut electric activity.

Dental pulp stem cells as a therapy for congenital entero-neuropathy

“…To generate pseudocolour images, the eld potential data were thinned 100-1000-fold in the time domain and bandpass ltered at 0.25-30 Hz (Kaiseki Excel add-in software, Kyowa, Tokyo, Japan). At certain recording times, the 8×8 eld potentials were interpolated by a spline function with 50 points between each potential using MATLAB (MathWorks, Natick, MA, USA) 53 . To reconstitute smooth potential images, the amplitude of the eld potential in each ME was compensated by the linear spectrum at 0.1-15 Hz 51 .…”

“…Each recording electrode was a square (~50 μm × 50 μm) made from platinum black nanoparticles, which increased the surface area by ~200-fold to 0.5 mm 2 . The capacitance (CME) and resistance (RME) of each microelectrode was 0.052 μF and 15 kΩ, respectively 51,53 , hence the impedance of the recording electrode at 0.1 Hz was estimated to be small enough [~31 MΩ = √ {1/(2π × 0.1 Hz × 0.052 μF) 2 + (15 kΩ) 2 }] to follow oscillating potentials when compared to the input impedance of the multi-channel ampli er (100 MΩ at 0.1 Hz). The e cacy of electrical signal transmission (Tr) was estimated to be ~95% at 0.1 Hz [100 MΩ / √ {(100 MΩ) 2 + (31 MΩ) 2 }].…”

Classification of Pacemaker Dynamics in the Mouse Intestine by Field Potential Microimaging

“…1A,B). From the capacitance ( C ME : 0.052 μF) and resistance ( R ME : 15 kΩ) of the sensing microelectrode, the estimated impedance was sufficiently low to follow a wide frequency range of electric signals (Taniguchi et al 2013; Iwata et al 2017). For instance, the impedance ( Z ME ) of the sensing electrode at 0.1 Hz [∼31 MΩ = √ {1/(2π × 0.1 Hz × 0.052 μF) 2 + (15 kΩ) 2 }] was sufficiently small compared with the input resistance of the multi-channel amplifier used in this study (100 MΩ).…”

Dental pulp stem cells as a therapy for congenital entero-neuropathy

“…Each recording electrode was a square (~50 μm × 50 μm) made from platinum black nanoparticles, which increased the surface area by ~200-fold to 0.5 mm 2 . The capacitance (CME) and resistance (RME) of each microelectrode was 0.052 μF and 15 kΩ, respectively 51,53 , hence the impedance of the recording electrode at 0. Comparisons (vs. JF1 mice) were made using the log-rank test.…”