Southan, Andrew Paul;
(1992)
Actions and interactions of high pressure and general anaesthetics in rat hippocampal Ca1 neurones.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
The thesis is divided into two experimental sections: the first concerns the actions of general anaesthetics on rat hippocampal CA1 neurones at atmospheric pressure. The second investigates some properties of CA1 neurones under high helium pressure. The general anaesthetics studied at one atmosphere were enflurane, isoflurane, halothane, ketamine and methohexitone. Antidromic field potential measurements were taken in the absence and presence of the anaesthetics in order to assess changes in axonal/somatic excitability. Accommodation behaviour of CA1 neurones was also investigated in intracellular experiments with the above anaesthetics. The principal findings were that the anaesthetics studied decreased the amplitude of the antidromic field potential and induced hyperpolarization, with the exception of ketamine which enhanced antidromic responses at low concentration and had mixed effects upon the resting potential. Halothane also induced a second antidromic population spike. The inhalation anaesthetics (enflurane, isoflurane, halothane) all blocked accommodation. Ketamine was found to slightly compromise accommodation, whilst methohexitone had mixed effects. A voltage-clamp study indicated that enflurane reduced the M-current of CA1 neurones. CA1 neurone responses to helium pressure (up to 13.3MPa) were investigated using a purpose built pressure chamber designed to facilitate intracellular recording. In field potential experiments antidromic and orthodromic responses (to both single and paired pulses) were studied at one atmosphere and following compression. Responses were found to be mixed at elevated pressure. Some preparations were found to be unaffected by pressure whilst others became more excitable. Ketamine and methohexitone were found to have similar actions at 10MPa to their actions at 0.1 MPa. Intracellular measurements were made at pressure (5MPa and 10MPa). Resting membrane potential, input resistance and threshold potential were found to be unaffected by pressure. High pressure was found to block accommodation and reduce the associated AHP in CA1 neurones.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Actions and interactions of high pressure and general anaesthetics in rat hippocampal Ca1 neurones |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Thesis digitised by ProQuest. |
| Keywords: | Biological sciences; Hippocampus |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10120961 |
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