%0 Journal Article
%T Determinants of the daily rhythm of blood fluidity
%A Tatsushi Kimura
%A Tsutomu Inamizu
%A Kiyokazu Sekikawa
%A Masayuki Kakehashi
%A Kiyoshi Onari
%J Journal of Circadian Rhythms
%D 2009
%I BioMed Central
%R 10.1186/1740-3391-7-7
%X The subjects were nine young males. We measured the physiological parameters and performed hematological and biochemical analyses. We repeated the measurements six times during the day at 7:30 (just after getting up and before breakfast), 10:00, 13:30 (after lunch), 16:30, 19:30 (after dinner), and 21:30. The subjects performed sedentary work all day, and the contents and time of the meals were uniform. Investigation of blood rheology was based on Kikuchi's microchannel method.Blood passage time varied significantly with time of day. Stepwise regression analysis was used to determine the significant factors affecting blood passage time. Body temperature, heartbeat, hematocrit, white blood cell and total cholesterol were significant determinants of blood passage time.We confirmed that blood fluidity has a daily rhythm. In addition, we found that the determinants of blood fluidity included physiological parameters such as body temperature and heartbeat, hematological parameters such as hematocrit, and white blood cell and total cholesterol.Research conducted during the past half century has made it clear that virtually all physiological phenomena in the living body exhibit daily rhythmicity. Refinetti and Menaker [1] reviewed the literature on the circadian rhythm of body temperature, emphasizing species differences, development and aging, and the relationships between the circadian rhythm of body temperature and the circadian rhythm of daily activity. In the clinical field, previous studies [2-4] have documented an important role of circadian rhythmicity in cardiovascular health. Uehara et al [5] reported that platelet aggregation and blood coagulation have a time course change and that these may have implications for cerebral infarction. On the other hand, in the sports field, it is common for athletes to adjust the hour of rising and timing of warming up according to the start of a game. It is necessary to adjust the hour of rising to achieve the best performance b
%U http://www.jcircadianrhythms.com/content/7/1/7