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KMID : 0351619730140020215
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Kyungpook Medical Journal
1973 Volume.14 No. 2 p.215 ~ p.225
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Effects of Parasympathetic Activity on the Production and Secretion of Pulmonary Surfactant of Rabbits
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Abstract
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Conflicting results have teen reported on the effects of the parasympathetic activity in the production and secretion of the lung surfactant. In the present study, an attempt was made to clarify the possible neurohumoral mechanism in the production and secretion of the lung surfactant, and two types of the parasympathetic activity were elicited on the rabbits, namely ; exacerbation in which acetylcholine and bilateral cervical electrical vagal stimulation were employed, and blockade in which atropine and bilateral cervical vagotomy were employed. The activities of the surfactant of the lung washings with the modified Langmuir-Wilhelmy balance were studied as well as the electron microscopic observations of the type Ⅱ alveolar cells were made from the rabbit so treated, and a comparison was made with the normal. The total protein content of lung washings was also measured.
Study of the surface tension :
The maximal and minimal surface tension, stability index and the total protein content of the normal rabbit lung washings were 55.9dyne/cm, 5.3dyne/cm, 1.7 and 165.5㎍/ml, respectively. The minimal surface tension of the lung washings was increased in all the groups studied with the most significant increase in the vagotomized group.
Measurement of protein :
The total protein content of the lung washings was significantly increased in the vagotomized and electrical vagal stimulated rabbits. But in the acetylcholine treated and atropinized rabbits it was slightly increased or within the normal limit.
Electron microscopic study :
In the normal rabbit, the type Ⅱ alveolar cell displayed abundant inclusions with the characteristic deeply osmiophilic lamellae, and inclusion could be found throughout the cytoplasm. The endoplasmic reticulum was abundant, but the cisternae remained inconspicuous. However, mitochondria and Golgi vesicles were regularly distributed. In electrical vagal stimulated rabbits, the type Ⅱ alveolar cell displayed conspicuous osmiophilic inclusions. Endeplasmic reticulum cisternae were massively dilated and contained abundant osmiophilic materials. In the vagotomized and atropinized rabbits, a moderate alteration of the osmiophilic inclusion bodies of type Ⅱ alveoler cell was produced, consisting of attenuation of the typical lamellae and formation of vacuoles. Endoplasmic reticulum, mitochondria and Golgi vesicle were regularly distributed.
Both the exacerbation and blockade of the parasympathetic activity decreased the activity of pulmonary surfactant, but morphologically the enhancement of the secretory processes by parasympathetic effect, and degenerative changes of micro structures of type Ⅱalveolar cell by anticholinergic effect were produced. The above results indicate that the production and secretion of the surfactant by the type Ⅱ alveolar cell may be governed by neurohumoral mechanism.
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