PubMed · 5760515
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M Mitolo. 1968. Electromyography on aging.. https://doi.org/10.1159/000211642
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We describe here methods for dissociating retinal ganglion cells from adult goldfish and rat without proteolytic enzymes, and show responses of ganglion cells isolated this way to step-wise voltage changes and fluctuating current injections. Taking advantage of the laminar organization of vertebrate retinas, photoreceptors and other cells were lifted away from the distal side of freshly isolated goldfish retinas, after contact with pieces of membrane filter. Likewise, cells were sliced away from the distal side of freshly isolated rat retinas, after these adhered to a membrane filter. The remaining portions of retina were incubated in an enzyme-free, low Ca2+ solution, and triturated. After aliquots of the resulting cell suspension were plated, ganglion cells could be identified by dye retrogradely transported via the optic nerve. These cells showed no obvious morphological degeneration for several days of culture. Perforated-patch whole-cell recordings showed that the goldfish ganglion cells spike tonically in response to depolarizing constant current injections, that these spikes are temporally precise in response to fluctuating current injections, and that the largest voltage-gated Na+ currents of these cells were larger than those of ganglion cells isolated with a neutral protease.
We have developed an optical telemetry system for recording electrical signals associated with muscle and neuronal activities from freely walking crayfish under water. The device was made from conventional electronic parts which are commercially available, utilizing infrared light (880 nm) for signal transmission. Two or four channels of biological signals were multiplexed, the voltage of each data point modulated to the duration of subcarrier pulses and further to the interval of narrower carrier pulses that directly drove the infrared light emission diode (IRLED) under water. The light-pulse modulated signals were received by photodiodes and demodulated to restore the original two or four channel signals. Electrical recordings using wired electrodes and conventional amplifiers revealed that the optically transmitted signals were consistent with the wire-transmitted ones. In order to test the performance of this system, we recorded electromyograms (EMGs) from the second and third walking legs on each side of crayfish together with the neuronal activity in the ventral nerve cord. The results confirmed our previous observation in tethered crayfish that the background tonus of leg muscles showed an increase preceding their rhythmic activation.
The effectiveness of grafts of olfactory ensheathing cells (OECs) as a means of promoting functional reconnection of regenerating primary afferent fibers was investigated following dorsal root injury. Adult rats were subjected to dorsal root section and reanastomosis and at the same operation a suspension of purified OECs was injected at the dorsal root entry zone and/or into the sectioned dorsal root. Regeneration of dorsal root fibers was then assessed after a survival period ranging from 1 to 6 months. In 11 animals, electrophysiology was used to look for evidence of functional reconnection of regenerating dorsal root fibers. However, electrical stimulation of lesioned dorsal roots failed to evoke detectable cord dorsum or field potentials within the spinal cord of any of the animals examined, indicating that reconnection of regenerating fibers with spinal cord neurones had not occurred. In a further 11 rats, immunocytochemical labeling and biotin dextran tracing of afferent fibers in the lesioned roots was used to determine whether regenerating fibers were able to grow into the spinal cord in the presence of an OEC graft. Although a few afferent fibers could be seen to extend for a limited distance into the spinal cord, similar minimal in-growth was seen in control animals that had not been injected with OECs. We therefore conclude that OEC grafts are of little or no advantage in promoting the in-growth of regenerating afferent fibers at the dorsal root entry zone following rhizotomy.