低酸素呼吸の副腎髄質分泌に及ぼす影響 : 副腎静脈留置カニューレ犬による実験的研究
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概要
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Many studies concerning the effect of hypoxia on adrenal medullary secretion had been reported, but most of these are with biological method observating such changes as increase of heart rate, elevation of blood pressure or blood sugar. In our department systemic studies concerning the effect of hypoxia on visceral circulation and metabolism were carried out and Ohta, one of the author's co-workers, reported adrenocortical response recently. This study was designed to make clear the adrenal medullary response to hypoxia directly by estimating catecholamine with chemical assay method. Materials and Methods Adult mongrel dogs weighing about 10kg were cannulated in lumbo-adrenal vein by the method of Hume-Nelson (modification of Katsuki et al.). Twenty-four hours after operation, the experiments were performed under sodium pentobarbital anesthesia. Dogs were divided into 4 groups: 1) room air control group, 2) 10% O_2 group, 3) 7% O_2 group and 4) 5% O_2 group, according to the concentration of low oxygen gas mixture which were inhaled from Douglas bag through the tracheal cannula for 20 to 30 minutes. Blood samples for determinating adrenal catecholamine secretion were collected before and at the each 20 minutes interval until 80 minutes after inhalation. The determination of catecholamine (adrenaline and noradrenaline) was made THI method modified by Hashimoto et al. To estimate hypoxic grade, arterial blood samples were taken from femoral artery before and 20 minutes after the beginning of inhalation and determined the oxygen saturation by Van Slyke method. Results and Comments In control group, there was no significant changes in catecholamine secretion until 30 minutes after beginning of inhalation, but in 40 minutes or more after slight increase of adrenaline secretion was observed. This suggested the effect of experimental procedure such as bleeding, anesthesia etc. Therefore the data in 10 or 20 minutes should be noticed to discuss the effect of hypoxia. Adrenaline secretion increased distinctly in all hypoxic groups at 10 and 20 minutes in comparison with control. Although there were no difference of its secretion rate between three groups at 10 minutes, 20 minutes value related to the severity of hypoxemia. On the other hand, no significant change of noradrenaline secretion was seen in all groups except in one case of 5% O_2 group with slight increase at 20 minutes. From these facts it was clear that hypoxia stimulated the adrenal medulla and caused marked increase of adrenaline. Heart rate increased slightly at 10 minutes in 5% O_2 group, but in all groups it tended to decrease at 20 minutes in spite of the high adrenaline secretion. Arterial mean blood pressure also tended to fall at 20 minutes. These circulatory responses were paradoxical to the adrenal medullary hyperresponse.
- 社団法人日本循環器学会の論文
- 1972-05-20