Lepage O M, DesCôteaux L, Marcoux M, Tremblay A
Département de Médecine, Faculté de Médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec.
Can J Vet Res. 1991 Jan;55(1):5-10.
The purpose of the study was to determine whether there were circadian variations in serum osteocalcin in normal horses and to determine whether it was important to regulate the time of blood sampling in clinical investigations. Osteocalcin or bone Gla-protein (BGP), alkaline phosphatase, total calcium, phosphate and total protein were studied over a 24 h period. Blood samples were taken every 60 min from nine adult Standardbred horses. There was a correlation between serum levels of alkaline phosphatase (r = 0.3, p less than 0.01), phosphate (r = 0.42, p less than 0.01) and serum osteocalcin levels. There was a very marked individual effect on serum levels of osteocalcin and alkaline phosphatase (p less than 0.01). This effect was present for phosphate levels but not significant for total calcium. The individual effect was lower and time effect was higher for serum osteocalcin if the subjects were divided into two age groups, one of horses of five years or less (n = 4) and a second group older than five years (n = 5). In both groups a circadian rhythmicity was observed. Serum osteocalcin showed a biphasic pattern. Levels were constant during daytime (light period) and underwent significant variations during the night (dark period), going through a nadir at 2000 h and through a maximum peak at 0500 h. It was concluded that in normal horses the blood osteocalcin level follows a circadian variation. Also daytime (light period) seems to be the more appropriate period for blood sampling.
本研究的目的是确定正常马匹血清骨钙素是否存在昼夜变化，并确定在临床研究中规范采血时间是否重要。在24小时内对骨钙素或骨γ-羧基谷氨酸蛋白（BGP）、碱性磷酸酶、总钙、磷酸盐和总蛋白进行了研究。每隔60分钟从9匹成年标准赛马采集血样。碱性磷酸酶血清水平（r = 0.3，p小于0.01）、磷酸盐（r = 0.42，p小于0.01）与血清骨钙素水平之间存在相关性。血清骨钙素和碱性磷酸酶水平存在非常显著的个体效应（p小于0.01）。这种效应在磷酸盐水平上存在，但对总钙不显著。如果将受试者分为两个年龄组，一组为5岁及以下的马匹（n = 4），另一组为5岁以上的马匹（n = 5），则血清骨钙素的个体效应较低，时间效应较高。在两组中均观察到昼夜节律性。血清骨钙素呈双相模式。白天（光照期）水平恒定，夜间（黑暗期）发生显著变化，在2000时达到最低点，在0500时达到最高峰。得出的结论是，正常马匹血液中的骨钙素水平遵循昼夜变化。此外，白天（光照期）似乎是更合适的采血时间。
