Mesteig K, Tyler N J, Blix A S
Department of Arctic Biology and Institute of Medical Biology, University of Tromso, N-9037 Tromso, Norway.
Acta Physiol Scand. 2000 Oct;170(2):145-51. doi: 10.1046/j.1365-201x.2000.00767.x.
This study tested the hypothesis that the annual cycle in heart rate (HR) in reindeer is, at least in part, a consequence of seasonal fluctuation in voluntary-food intake. Heart rate and daily dry matter voluntary-food intake (DDMVFI) were recorded in two captive female reindeer (Rangifer tarandus tarandus) from April 1995 to August 1996. Heart rate was measured continuously in each animal for 20-24 h for 7 days each month using Polar(R) Sport Testers (PST); DDMVFI was measured in each animal daily for 17 months. Modal daily heart rate (MDHR) and DDMVFI fluctuated seasonally in close synchrony, both reaching maxima in July and minima in January. The relationship between HR and DDMVFI was investigated experimentally by manipulating the level of feeding in a stepwise manner in May, when appetite was low and in August, when DDMVFI was close to maximum. Heart rate showed stepwise changes in close synchrony with the changes in levels of feeding. These results suggest that the seasonal increase in HR in summer is a consequence of increased food intake and, likewise, decreased HR in winter is a consequence of reduced food intake. The observed relationship between food intake and HR presumably reflects changes in cardiac output and/or the rate of flow of blood to the gastrointestinal tract which are influenced by meal size.
驯鹿心率（HR）的年度周期至少部分是自愿食物摄入量季节性波动的结果。1995年4月至1996年8月，在两只圈养的雌性驯鹿（Rangifer tarandus tarandus）中记录了心率和每日干物质自愿食物摄入量（DDMVFI）。每月使用Polar（R）运动测试仪（PST）对每只动物连续测量20 - 24小时的心率，共测量7天；对每只动物每天测量DDMVFI，持续17个月。每日平均心率（MDHR）和DDMVFI呈现季节性同步波动，均在7月达到最大值，1月达到最小值。通过在5月（食欲较低时）和8月（DDMVFI接近最大值时）逐步调整喂食水平，对心率与DDMVFI之间的关系进行了实验研究。心率与喂食水平的变化呈现同步的逐步变化。这些结果表明，夏季心率的季节性增加是食物摄入量增加的结果，同样，冬季心率降低是食物摄入量减少的结果。观察到的食物摄入量与心率之间的关系可能反映了心输出量和/或流向胃肠道的血流速度的变化，这些变化受进食量的影响。
