Experiment-based Applications

Synaptic Plasticity

Single Unit Activity

Rhythmic Activity

Muscle Propagation
and Pacing

QT Prolongation

Pharmacology and
Drug Testing

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Preparation-Based Applications

MED64 APPLICATIONS

Muscle Propagation and Pacing

MED probes are ideal for studying primary cardiomyocyte cultures and cell lines (e.g. HL-1) or for recording from acute cardiac tissue preparations. The MED probe’s high-capacitance electrodes allow delivery of stimulus current as high as 200μA through any of the 64 electrodes, enabling acquisition of “paced” or spontaneous signals. Simultaneous recording from the 64 electrodes allows 2-D propagation patterns and velocities to be observed.

Example 1: Spontaneous and paced signals in primary cardiomyocyte cultures

A	B (50μV, 10ms /Div)
C (50μV, 10ms /Div)	D

A. Fluorescence micrograph of cardiomyocyte cultures on MED probe. (MED-P545A; 450μm inter-polar distance)
B. Spontaneous responses obtained from 64 electrodes.
C. Signals evoked by stimulation at two adjacent electrodes.
D. Phase map of pacing activity. Each color shows the latency (ms) of the responses evoked by stimulation.

Courtesy of Drs. Lee and Kodama, Nagoya University, Japan

Example 2: Left atrium paced response

A	B (2.0mV, 20ms/Div)
C Courtesy of Dr. H.Yeh, Mackay Memorial Hospital, Taiwan
A: Micrograph of rat left atrium on MED probe (MED-P545A; 450μm inter-polar distance). B: Paced responses evoked by stimulation at the two electrodes (blank panels) on the MED probe. C: Propagation of the paced responses. Each time frame shows the computed two-dimensional field potential distribution over time. Positive potentials are white and negative potentials are black.

Example 3: Recordings from smooth muscle

Spontaneous potentials generated by a smooth muscle (circular & longitudinal) preparation obtained from a small segment of guinea pig intestine. The preparation was placed on a MED probe (MED-P545A, 450µm inter-polar distance) and held down using nylon mesh and slice anchor (as typically done with brain slices).

Spread of pacemaker activity along circular muscle

(a) This series of frames illustrates the spread of pacemaker activity seen along circular muscle in the presence of 1μM Nifedipine and 250nM TTX. The voltages recorded at each electrode are pseudo-color coded (scale at right) and oriented as shown in the first panel. The frames were taken 50msec apart, and are displayed temporally from left to right for the top, and then the bottom rows. As shown, the peak negative potentials (yellow) spread along the orientation of the circular muscle (left to right), which was preferentially oriented to be in closest contact with the electrode array.

(b) Latency maps of the peak negative potentials (left graph) and positive potentials (right graph) also illustrate the phase differences observed in spontaneous pacemaker activity. The phase map of the negative peak is, as shown in a, consistent with the spread of pacemaker activity along the direction in which the circular muscle is oriented. The map of the positive peak is consistent with this, but also suggests spread along the direction (bottom to top) of the longitudinal muscle.

Courtesy of Dr. Nakayama, Dept. of Cell Physiology, Graduate school of medicine, Nagoya University, Japan