THE MECHANISM OF THE REFLEX APNOEA CAUSED BY NICOTINE, ESPECIALLY ON THE SPECIES DIFFERENCE BETWEEN CAT AND RABBIT

Abstract

It has been reported that a brief apnoea lasting a few seconds, is observed immediately after the intravenous injection of many compounds ; nicotine (Dawes, 1947, Nagasaki, 1953, Paintal, 1955, Domaye, 1955), antihistaminic drugs (Winder, 1947, Aviado, 1950, Jones, 1952), phenyl diguanide (Paintal, 1953, 1955, Dawes, 1950, 1951, 1952), serotonine (Schneider, 1953, 1954, Comroe, 1953, Paintal, 1955) and adenosine triphosphate (Emmelin, 1948) etc.. Furthermore it has been shown that some of these apnoeas are reflex and the receptors responsible for the reflex are in the lungs, because the apnoeas are abolished by bilateral vagotomy and are observed easily by the administration of the drugs into right ventricle or pulmonary artery, but are not observed in left ventricle of heart.On the nicotine apnoea, Domaye (1955) described that the apnoea occured reflexly in the expiratory position in cats and dogs, while Nagasaki (1953) and Kimura (1954) observed one in the inspiratory position in rabbits. The similar observation in different species has been reported on the apnoea caused by serotonine (Schneider, 1954), antihistaminic drugs (Takasaki, 1957), phenyl diguanide (Dawes, 1951 a, b) and isothiourea derivatives (Dawes, 1950). However, no reportors have elucidated it in detail.The present experiments are an attempt to contribute something to elucidate the mechanism of nicotine apnoea, especially the species difference between cats and rabbits (expiratory and inspiratory).