The Nature of Non-Adrenergic Inhibition in the Mammalian Intestine


Responses to non-adrenergic inhibitory nerves have been obtained and pharmacologically analysed in isolated intestinal preparations from rabbits, guinea pigs and cats. The nerves were found to differ from adrenergic sympathetic nerves in a number of ways. Their threshold and optimal frequency for electrical stimulation was lower than that of sympathetic nerves and in contrast to sympathetic nerves the peripheral ganglia were situated in or close to the tissue innervated. Responses to non-sympathetic nerves persisted after abolition of sympathetic responses by either adrenergic neurone blocking drugs or by mixtures of a and 8B adrenoceptor blocking drugs. Non-adrenergic inhibitory responses could be imitated by both nicotine and 5-hydroxytryptamine. Like sympathetic responses the non-adrenergic nerve responses were impaired by reserpine. In the guinea pig isolated colon preparation, it was demonstrated that non-adrenergic nerves have extrinsic connections via the pelvic nerves. A mixture of pempidine and bufotenine abolished responses to pelvic nerve stimulation, suggesting the involvement of both 5-hydroxytryptamine and acetylcholine as ganglionic transmitters. Unsuccessful attempts have been made to isolate and identify the postganglionic transmitter substance from nonadrenergic sympathetic nerves. In addition, a variety of biogenic substances have been examined as potential transmitter substances. Particular attention was paid to the adenine nucleotides in view of recent reports suggesting these as likely transmitter substances in non-adrenergic inhibitory nerves. Little evidence was found to support this concept and it is suggested that the term "purinergic nerves" to describe these nerves is premature. The phenomenon of "rebound contraction" following transmural stimulation of isolated intestinal preparations has been studied. It is suggested that the major part of the response is due to stimulation of cholinergic nerves within the intestinal wall. A short examination has been made of the sympathetic nerve blocking action of B-adrenoceptor blocking substances. The evidence suggests that this action is pre-synaptic but differs from that of guanethidine.

Divisions: College of Health & Life Sciences
Additional Information: Copyright © Warren, 1973. P.R. Warren asserts their moral right to be identified as the author of this thesis. This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without appropriate permission or acknowledgement. If you have discovered material in Aston Publications Explorer which is unlawful e.g. breaches copyright, (either yours or that of a third party) or any other law, including but not limited to those relating to patent, trademark, confidentiality, data protection, obscenity, defamation, libel, then please read our Takedown Policy and contact the service immediately.
Institution: Aston University
Uncontrolled Keywords: nature,non-adrenergic inhibition,mammalian intestine
Last Modified: 28 Jun 2024 07:06
Date Deposited: 24 Jan 2011 15:29
Completed Date: 1973
Authors: Warren, Peter R.

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