Electrophysiology of isolated mammalian spinal cord
Electrophysiology of isolated mammalian spinal cord
Previous studies showed that the isolated hemisected mammalian spinal cord survived well in vitro; hence the physiological and pharmacological properties could be investigated. This work describes the development and use of an in vitro whole spinal cord - peripheral nerve preparation to investigate the ipsilateral and contralateral reflexes evoked in the flexor (tibial) and extensor (femoral) nerve trunks of the thigh of the golden hamster. The survival of an isolated peripheral nerve (sural) and of the dorsal root - ventral root reflexes (DR - VRR) in the hemisected spinal cord preparation were investigated. Spontaneous activity could be recorded from the dorsal and ventral roots. The activity in the dorsal roots was inhibited by magnesium (2.0 mM) and that in the ventral roots was inhibited by magnesium (0.1 mM). The higher sensitivity of the ventral root activity to magnesium indicates that NMDA receptors may be involved in this activity. Stimulation of the lumbar dorsal roots evoked a fast short latency synchronous (monosynaptic) reflex response and/or later more diffuse asynchronous (polysynaptic) responses in the ipsilateral tibial and femoral nerves. The ipsilateral tibial response had a mean delay of 15.9 ± 1.2 msec (Mean ± S.E., n. = 21) and the ipsilateral femoral response had a mean delay of 14.4 ± 0.5 msec (n. = 14). The responses evoked in the contralateral tibial and femoral nerves following stimulation of the lumbar dorsal roots were polysynaptic. The mean delay of the responses in the contralateral tibial nerve was 28.3 ± 2.3 msec (n. = 13) and the mean delay of the responses in the contralateral femoral nerve was 25.5 ± 7.7 msec (n. = 3). Stimulation of the tibial nerve trunk instead of the dorsal roots evoked responses in the contralateral tibial nerve with a mean delay of 26.6 ± 1.7 msec (n. = 5), but only one recording was obtained from the contralateral femoral nerve with a delay of 37.5 msec. Stimulation of the femoral nerve trunk evoked responses in the contralateral tibial nerve with a mean delay of 36.4 ± 3.2 msec (n. = 7), but only once in the contralateral femoral nerve with a delay of 51.5 msec. The investigation of dorsal root - dorsal root reflexes (DR - DRR) showed that crossed DR - DRRs persisted even after partial hemisection had been performed, but the delay of the crossed reflexes after hemisection (41.9 ± 7.1 msec) was much longer than before hemisection (18.3 ± 1.8 msec). This suggests that there is a connecting network between the dorsal horns through which the impulses travel up, down and across the spinal cord. (DX85694)
University of Southampton
Rakkah, Nabeeh Ibrahim Ali
1988
Rakkah, Nabeeh Ibrahim Ali
Rakkah, Nabeeh Ibrahim Ali
(1988)
Electrophysiology of isolated mammalian spinal cord.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Previous studies showed that the isolated hemisected mammalian spinal cord survived well in vitro; hence the physiological and pharmacological properties could be investigated. This work describes the development and use of an in vitro whole spinal cord - peripheral nerve preparation to investigate the ipsilateral and contralateral reflexes evoked in the flexor (tibial) and extensor (femoral) nerve trunks of the thigh of the golden hamster. The survival of an isolated peripheral nerve (sural) and of the dorsal root - ventral root reflexes (DR - VRR) in the hemisected spinal cord preparation were investigated. Spontaneous activity could be recorded from the dorsal and ventral roots. The activity in the dorsal roots was inhibited by magnesium (2.0 mM) and that in the ventral roots was inhibited by magnesium (0.1 mM). The higher sensitivity of the ventral root activity to magnesium indicates that NMDA receptors may be involved in this activity. Stimulation of the lumbar dorsal roots evoked a fast short latency synchronous (monosynaptic) reflex response and/or later more diffuse asynchronous (polysynaptic) responses in the ipsilateral tibial and femoral nerves. The ipsilateral tibial response had a mean delay of 15.9 ± 1.2 msec (Mean ± S.E., n. = 21) and the ipsilateral femoral response had a mean delay of 14.4 ± 0.5 msec (n. = 14). The responses evoked in the contralateral tibial and femoral nerves following stimulation of the lumbar dorsal roots were polysynaptic. The mean delay of the responses in the contralateral tibial nerve was 28.3 ± 2.3 msec (n. = 13) and the mean delay of the responses in the contralateral femoral nerve was 25.5 ± 7.7 msec (n. = 3). Stimulation of the tibial nerve trunk instead of the dorsal roots evoked responses in the contralateral tibial nerve with a mean delay of 26.6 ± 1.7 msec (n. = 5), but only one recording was obtained from the contralateral femoral nerve with a delay of 37.5 msec. Stimulation of the femoral nerve trunk evoked responses in the contralateral tibial nerve with a mean delay of 36.4 ± 3.2 msec (n. = 7), but only once in the contralateral femoral nerve with a delay of 51.5 msec. The investigation of dorsal root - dorsal root reflexes (DR - DRR) showed that crossed DR - DRRs persisted even after partial hemisection had been performed, but the delay of the crossed reflexes after hemisection (41.9 ± 7.1 msec) was much longer than before hemisection (18.3 ± 1.8 msec). This suggests that there is a connecting network between the dorsal horns through which the impulses travel up, down and across the spinal cord. (DX85694)
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Published date: 1988
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Local EPrints ID: 460959
URI: http://eprints.soton.ac.uk/id/eprint/460959
PURE UUID: ff4a1c63-9685-4328-8000-e3692782e1c8
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Date deposited: 04 Jul 2022 18:32
Last modified: 04 Jul 2022 18:32
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Author:
Nabeeh Ibrahim Ali Rakkah
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