Lack Of Respiratory Effects Of Nicotine Applied To The Caudal Medullary Raphé

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Title: Lack Of Respiratory Effects Of Nicotine Applied To The Caudal Medullary Raphé
Author: Bates, Nicole
Abstract: Breathing is an involuntary and automatic process initiated by a network of neurons within the brainstem . These neurons are affected by a number of factors (mechanical , electrical and chemical ) that help modulate the frequency and pattern of breathing . Three respiratory chemosensitive sites have traditionally been described on the ventral medullary surface . These sites are affected by the pH of the cerebrospinal fluid (CSF ) bathing the brain and by chemicals dissolved within the CSF . More recently , additional sites have been described with chemosensitive activity and of these the medullary raphé has received the most attention . Although the dangers of smoking is well known , people have continued with this habit . Of concern are women who smoke and of particular concern are pregnant women who continue to smoke during their pregnancy . This is of concern because of the many chemicals contained within cigarette smoke , nicotine is particularly potent at affecting the health and well -being of the mother and fetus (and infant ) because nicotine can enter the circulation within minutes of ingesting cigarette smoke . I am interested in how nicotine affects breathing . I therefore looked at the effects of nicotine on the caudal raphé , the raphé magnus . Nicotine injected into the raphé magnus did not affect the animal's respiratory activity , even in pharmacological doses (P > 0 .05 ) . Neither respiratory frequency , amplitude , as well as inspiratory or expiratory time were affected . Administration of increaseing levels of carbon dioxide before and after nicotine injections caused vigorous changes in respiratory activity . I tested the effectiveness of the drug by injecting it into a known nicotine -sensitive region (the caudal chemosensitive region ) which resulted in respiratory stimulation . It appears that the raphé magnus is not responsive to nicotine . Immunohistomical studies should now be undertaken to determine if there are indeed nicotinic receptors at this location .
URI: http : / /hdl .handle .net /10106 /998
Date: 2008-08-08

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Lack Of Respiratory Effects Of Nicotine Applied To The Caudal Medullary Raphé. Available electronically from http : / /hdl .handle .net /10106 /998 .

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