Studies of Skin Blood Volume in Skin Microcirculation (II) Seasonal Fluctuation of Skin Blood Volume and Skin Temperature in Man

The skin blood volume and the skin temperature were measured on 18 sites of the skin surface of males and females each. The measurement were made at a temperature of 12.4℃ in May, 22.6℃ in July, 13.6℃ in October and of -1.3℃ in January using a topographical photoelectric plethysmograph with transistor and by a thermister thermometer. The results were as follows; 1) The skin blood volume shows a gradual increase in spring and summer following winter, and decreases in autumn and winter following sammer. The same tendency was seen in skin temperature. In females this tendency was enhanced in winter. 2) The skin blood volume was larger in autumn than in spring, and the skin temperature was lower in autumn in spite of the high room temperature. These phenomena showed a congestive tendency in autum as compared with that in spring. 3) The skin temperature was somewhat lower in winter, but the skin blood volume was higher in females. These phenomena are brought about by the considerably lower temperature than the critical temperature. 4) Regional specifity of seasonal variations of the skin blood volume are observed. In the both trunk and adjacent regions, however, the skin blood volume and the skin temperture do not show too larger seasonal variation. But in the limbs especially in the extremeties such as the hands, feet, fingers and toes, the skin blood volume shows a small variation in the first half of the warm and cold seasons, and it is larger in the latter half, and the skin temperature shows greater variations in the warmer seasons. The frontal region shows a comformity with the external conditions circumstances, and resistance to severe circumstances. 5) It was concluded that the measurment of skin blood volume is important for the studies of the skin microcirculation