潜水艦1か月行動による紫外線遮蔽のビタミンD代謝に及ぼす影響について

Abstract

Blood and urine biochemical markers of vitamin D and bone metabolism were analyzed in the crew of a Japanese diesel-electric submarine before and after a four-week patrol cruise, to investigate the influences of a sunlight-deprived environment on vitamin D homeostasis and bone metabolism. Subjects were 20 crew members (aged from 21 to 41 years with a mean +/- SD of 28.1 +/- 5.1 years) of a 'Yushio' Class diesel electric submarine. Blood and urine specimens taken from the subjects before and after the patrol were compared. There were no signs or symptoms caused by the abnormal calcium or vitamin D metabolism among the subjects during and after the cruise. However, serum calcium and phosphorus increased remarkably, and 25-hydroxy-vitamin D (25(OH)D), urinary phosphorus, pyridinorine (Pyr) and deoxy-pyridinorine (d-Pyr) showed significant decreases after the patrol, while levels of 1,25-dihydroxyvitamin D (1,25(OH)2D) and urinary calcium were unchanged. There was a significant positive correlation between the change of 25(OH)D concentration and age; the decrease of 25(OH)D tended to be larger in the younger subjects. According to the result that the concentration of 1,25(OH)2D was well preserved despite the significant decrease of its precursor, 25(OH)D, some compensation mechanisms, such as activation of renal enzymes, for the decreased cutaneous vitamin D synthesis due to deprived UV irradiation was considered to be established within one month.

海上自衛隊の潜水艦乗員20名(平均年齢±標準偏差;28.1±5.1歳)を対象として、4週間にわたる潜水艦行動の前後におけるビタミンDとカルシウム代謝に関する各種生化学的指標を測定した。その結果、行動前後で血清カルシウムとリンは有意に上昇し、血中25-hydroxy-vitamin D(25(OH)D)と尿中リン、ピリジノリン、デオキシピリジノリンは有意に減少していた。活性型ビタミンD(1,25-dihydroxyvitamin D;1,25(OH)2D)と尿中カルシウムに変化はなかった。25(OH)Dの変化と年齢には有意の相関があり、若年者では25(OH)Dの減少が大きい傾向が見られた。紫外線刺激により皮膚で生成される前駆物質の25(OH)Dが減少しているのに対し、1,25(OH)2Dには変化が見られなかったことから、腎臓における活性化調節などによる何らかの代償機構が1か月以内に生じていることが示唆された。