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Abstract

Acetylcholine was first synthesized by Baeyer in 1867. At
the same time it was only of chemical interest but decades later
its powerful pharmacological effects were noted: Hunt and Taveau
pointed out the role of acetylcholine in lowering blood-pressure (1).
Dale and his co-workers demonstrated that acetylcholine is a chemical
mediator of the nerve impulses at parasympathetic endings (2). Thus
the notion of chemical mediation that had been introduced by Elliot
in respect of adrenalin (3) was extended to the physiology of
ganglionic synapses and neuromuscular junctions (4). This hypothesis
met with some opposition among neurophysiologists; objections to it
were reviewed by Eccles (5). For example stransmission or nerve
impulses across the neuromuscular junctions and synapses occurs
within milliseconds and chemical mediation by acetylcholine cannot
explain this phenomenon. Fulton (6) and Erlanger (7) considered
the extremely short interval for the effect of the axon-potential
which would preclude the intervention of any process dependent upon
substances released at the nerve endings.
Early hypotheses of chemical mediation were based on experiments
which employed methods of classical physiology and saccording to
Naohmansohn and his co-workers, did not permit an interpretation of
the precise function of the ester in the physiochemical mechanism
of the propogation of nerve impulses. Using suitable methods for
recording cellular functions such as conduction of nerve impulses
(8,9), Nachmansohn and his school came to the following conolusions(10):
The ester is released at the neuronal surface when a stimulus
reaches the nerve cell. Bythe action of acetylcholine the
permeability of the membrane to ions is increased and depolarization
' Occurs. The depolarized point becomes negative to the adjacent
region and a flow of current is generated. This flow of current
transmits the impulse to a neighbouring point where more acetylcholine
is released. The process is repeated and in this way the impulse
is propagated.
As the propagation of the nerve impulse hinges. on the
release and disappearance of the ester, the enzyme responsible for
the catalysis of the latter reaction attracted interest.
The aim of the work described in this part of the Thesis
was to isolate or purify the acetylcholine hydrolysing enzyme of
the sheep brain, a material which had received little attention
so far.
The question whether the tissue chosen was suitable for the
isolation of the enzyme may be considered through a brief survey of
the distribution of the enzyme.

Item Type:	Thesis - PhD
Authors/Creators:	Got, Katalin(Perl)
Keywords:	Cholinesterase
Copyright Holders:	The Author
Copyright Information:	Copyright 1964 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).
Additional Information:	Thesis (Ph.D.) - University of Tasmania, 1965. Includes bibliography
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