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J W PHILLIS

Publications and source records attributed to J W PHILLIS.

17 recordsLinked to original sources
PubMed1963

Actions of certain amines on cerebral cortical neurones.

A number of derivatives of tryptamine and phenethylamine, and certain other compounds, were tested on neurones in the cerebral cortex of cats by iontophoretic release from micro-pipettes. The characteristic action of many of these compounds was a depression of the neuronal discharge initiated by synaptic activity or by the application of L-glutamate; imidazolylacetic acid, dopamine, ephedrine and ergometrine were particularly effective. Catechol amines, hydroxytryptamines and imidazolylacetic acid had a relatively quick and rapidly reversible action, not unlike that of gamma-aminobutyric acid, whereas ephedrine and derivatives of lysergic acid diethylamide caused a slower and more prolonged depression of the amplitude of spikes, rather like atropine. Several compounds, including 5-hydroxytryptamine, adrenaline and ergometrine, could also excite the same neurone when larger amounts were applied. A few substances, such as dopa and methylergometrine, had a predominantly excitant action.

Amines↗
PubMed1961

Actions of aminoacids on the isolated hemisected spinal cord of the toad.

The actions of a series of amino-acids related to gamma-aminobutyric acid and glutamic acid have been determined upon the isolated and sagittally hemisected spinal cord of the toad, Bufo marinus. Slow and fast components of the ventral root reflex responses following dorsal root stimulation were depressed by gamma-aminobutyric acid and by a series of neutral amino-acids having a similar structure. The relative depressant potencies of the members of this series were determined by comparison of the concentrations of each required to cause the same reduction in the electrically integrated slow components of these reflex responses. Glutamic acid and closely related substances facilitated reflex responses in low concentrations and depressed these responses in high concentrations. The actions of these substances resulted in the depolarization of motoneurones which was recorded as a negative potential in the ventral root. The relative potencies of the substances were estimated from the concentrations of each required to produce negative potentials of the same magnitude.Several amino-acids not previously tested proved to have remarkably strong actions on this preparation. 3-Aminopropanesulphonic acid was the most potent depressant tested; homocysteic acid and N-methylaspartic acid were the most powerful excitatory substances. The D forms of optically active depressants or excitants were always stronger than the corresponding L forms where both enantiomorphs were available. Points of similarity and dissimilarity between these results and those of related investigations are discussed.

Amino Acids↗
PubMed1961

Action of some drugs on the dorsal root potentials of the isolated toad spinal cord.

A series of drugs which potentiate or antagonize transmission at cholinergic synapses have been tested on the slow depolarizing dorsal root potentials evoked by stimulation of adjacent dorsal and ventral roots. Some drugs acted specifically on the dorsal root potential evoked by ventral root stimulation. Dihydro-beta-erythroidine, atropine and acetylcholine depressed this potential, whilst anticholinesterase substances in low concentrations potentiated and in higher concentrations depressed it. It is concluded that the results offer some evidence for a cholinergic link in the pathway responsible for the generation of depolarizing potentials in the dorsal root subsequent to ventral root stimulation.

Ganglia, Spinal↗