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Biomedical subjects

W A Corrigall

Publications and source records attributed to W A Corrigall.

60 records · Page 4Linked to original sources
PubMed1980

A specific effect of morphine on evoked activity in the rat hippocampal slice.

The effect of morphine (0.5-50 microM) was examined on CA1 field potentials in the tranverse hippocampal slice. Morphine consistently produced an augmentation of evoked activity manifest as (i) a decrease in the threshold for generation of a population spike and (ii) generation of an additional population spike(s) whose amplitude was proportional to the position of the sampled response on its input/output curve. Both of these opiate effects were stereospecific and naloxone-reversible. Additional population spikes occurred in opiate medium with either orthodromic or antidromic activation of the pyramidal cells, and the antidromic effect was abolished when synaptic transmission was blocked, suggesting that morphine did not act directly upon the pyramidal cells. Recordings of population EPSPs in the dendrites of the pyramidal cells showed no changes due to opiate exposure near threshold. Opiate effects were mimicked by the gamma-aminobutyric acid (GABA) antagonist picrotoxin, and were partially to fully reversed by GABA itself, suggesting that disinhibition of pyramidal cells might be involved as a mechanism in this opiate effect. The data are evidence for a specific primary effect of morphine within the hippocampus in spite of the low numbers of opiate receptors in this brain region.

Animals↗
PubMed1980

Ethanol tolerance measured electrophysiologically in hippocampal slices and not in neuromuscular junctions from chronically ethanol-fed rats.

The electrophysiologically measured effects of perfused ethanol were examined in neuromuscular junctions and hippocampal slices removed concurrently from naive and ethanol-tolerant rats. At the neuromuscular junction, ethanol augmented the frequency height, and half-width of spontaneous miniature endplate potentials (Mepp). No tolerance was noted to these effects in junctions from ethanol-fed animals. Ethanol depressed the stratum radiatum evoked hippocampal CA1 population spike. Clearcut tolerance to this effect was noted in slices from chronically ethanol-fed animals.

Alcoholism↗
PubMed1978

Acetaldehyde affects mammalian neuromuscular transmission without observable postsynaptic effects.

Acetaldehyde, the first metabolite of ethanol, caused a reversible block of the end-plate potential (EPP) in the rat and mouse phrenic nerve--hemidiaphragm preparation. Decrease and block of the EPP occurred over a bath concentration range from 3 to 25 mM. The phrenic nerve compound action potential was blocked along with the EPP, and this block was not reversed by high bath Ca2+ concentration. The muscle action potential was unaffected even at concentrations up to 50 mM. Over the same concentration range (3--25 mM), miniature end-plate potential (MEPP) frequency sometimes decreased a few minutes after application, and over the ensuing 10--20 min would steadily increase to as much as 11 times the base-line frequency, particularly with higher doses. However, the shape of averaged MEPPs remained unchanged after acetaldehyde application, suggesting that this aldehyde does not have post-synaptic effects.

Acetaldehyde↗
PubMed1976

Electrophysiological studies of fetal mouse olifactory bulb explants during development of synaptic functions in culture.

Explants of 18- or 19-day fetal mouse olfactory bulb have been maintained in culture for periods up to 5 weeks. Compound action potentials can be evoked in the bulb explants by 1 day in vitro, and by 3-4 days, synaptically mediated slow wave discharges can be domonstrated in bicuculline (10(-5) m). The capability of the bulb explants to generate these slow-wave discharges has also been revealed by the introduction of picrotoxin (10(-5)m, d-tubocurarine (10(-4)m) and chloride-free medium, but not of strychnine (up to 3 X 10(-5)M. The data indicate early functional development of inhibitory, as well as excitatory, synaptic systems. In addition, the selective and reversible depression of these slow wave potentials by GABA (1-5 X 10(-4)M), but not by glycine (up to 3 X 10(-3)M), indicates a GABA-ergic component in the inhibitory network. Single unit extracellular recordings have been obtained from the presumptive mitral cells which, in culture, are spontaneously active even as early as 1-2 days after explantation. Correlative Bodian silver-impregnations demonstrate the presence of neurons in these explants which resemble typical mitral cells. Studies of mitral cells using paired stimuli suggest the development in vitro of an inhibitory system analogous to that known to suppress the excitability of their in situ counterparts following orthodromic or antidromic activation. These data, as well as the pharmacological sensitivities of the mitral cells in culture to GABA (5 X 10(-4)M) and bicuculline (10(-5)M), indicate that granule-to-mitral synapses may develop characteristic functions in olfactory bulb explants.

Action Potentials↗
PubMedDate not supplied

A simple modification to permit fast-flow perfusion of brain slices.

An adaptation of a tissue slice chamber is described that stabilizes brain slices during rapid perfusion. Comparison experiments show no deleterious effects of fast perfusion on field potential responses in hippocampal slices, and baseline responses appear to stabilize more quickly with the described modification.

Animals↗