title: Plasma hyaluronan concentration: no circadian rhythm but large effect of food intake in humans.
abstract: This study was designed to determine if a circadian rhythm in plasma hyaluronan concentration [HA] exists in the absence of physical activity, and if plasma [HA] is associated with feeding in human subjects. Five persons were studied under standardized conditions, blood samples being taken between 0600 and 2200 hours at 30-min intervals. Any orthostatic challenge and muscle activity was abolished by immobilization by a 6 degrees head-down bed-rest, and the effect of a quasi-continuous ingestion of energy compared a normal, three-portion diet of equivalent energy content or to fasting. Reproducibility of HA profiles on two consecutive half-days was also studied. A highly sensitive immunoassay was used to determine plasma [HA]. The data indicated that without physical activity and without food ingestion, [HA] was unchanged and displayed no diurnal rhythm. In addition, we observed that [HA] increased after the first food intake, peaking after 60 min, and concluded from our results that without ingestion of a larger meal, and sessions of postural or muscle activity, no circadian plasma [HA] rhythm exists.
authors.affiliation: Department of Physiology, School of Medicine, Karl-Franzens University, Graz, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Rössler
authors.forename: Z
authors.initials: Z
authors.lastname: László
authors.forename: E
authors.initials: E
authors.lastname: Kvas
authors.forename: H G
authors.initials: HG
authors.lastname: Hinghofer-Szalkay
mesh_terms: D000328:Adult; D001510:Bed Rest; D001794:Blood Pressure / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006820:Hyaluronic Acid / Q000097:blood*; D008196:Lymph / Q000502:physiology; D008297:Male; D011187:Posture / Q000502:physiology
chemical_list: D006820:Hyaluronic Acid