内蒙古草原布氏田鼠代谢率与身体器官的关系

动物代谢率存在差异的原因及其意义是进化生理学的一个核心问题。为了解代谢率的影响因素和功能意义, 我们测定了不同驯化条件下布氏田鼠(Microtus brandti) 的基础代谢率(basal metabolic rate , BMR) 、日能量消耗(daily energy expenditure , DEE) 和冷诱导的最大代谢率(maximum metabolic rate , MMR) , 分析了动物体内11 种器官、组织的重量与代谢率的关系。结果显示, 排除温度、光照、食物质量和体重的影响后, BMR 与心脏、肝脏、肾脏、胃和盲肠相关; DEE与心脏、肾脏、胃和盲肠相关; MMR 与脑重显著负相关。这表明: 在布氏田鼠体内存在着代谢活性器官, 主要包括心脏、肝脏、肾脏、胃和盲肠, 这些器官对BMR 有较大的贡献。动物的能量周转水平与体内“代谢机器” (metabolic machinery) 的大小相关连, 主要受到心脏、肾脏、胃和盲肠的影响。最大代谢率受脑重的影响。BMR 与MMR 的相关性不显著, 而BMR 与DEE 的相关性显著, 说明较高的BMR 有助于维持较高的DEE , 但不能维持较高的MMR。

Relationship Between Metabolic Rate and Organ Size in Brandt's Voles (Microtus brandti)

A central problem in evolutionary physiology concerns the physiological origin and functional significance of the great intra-and inter-specific variations in basal metabolic rate (BMR) . We analyzed the relationships between BMR, cold-induced maximum metabolic rate (MMR) , daily energy expenditure (DEE) and 11 body organs. Brandt's voles (Microtus brandti) were divided into 8 groups and acclimated in different photoperiod [ long day (16 Light : 8 Dark , and short day (8 Light : 16 Dark) ], temperature [ cold (5 ℃) , and warm (23 ℃) ], and diet quality [ high-fiber diet (56. 9 %) and low-fiber diet (35. 6 %) ] . After 3 weeks of acclimation , BMR , MMR and DEE were measured. Then voles were killed and 11 body organs were dissected. After removal of the effects of photoperiod, temperature, diet quality and body mass , we found that BMR was positively related to the sizes of heart, liver, kidneys, stomach' and cecum. The heart, kidneys, stomach, and cecum were highly correlated with DEE. And the brain was negatively correlated with MMR. These results indicate that there is a relationship between the sizes of internal organs and their contribution to BMR. And the energy turnover rate and thermogenic limitation were related to the metabolic machinery of the body. There is a significant correlation between BMR and DEE. However , no significant correlation between BMR and MMR was detected. Our results do not support the prediction that high BMR can generate high MMR, but support the prediction that high BMR can generate high DEE. Furthermore, the results in the present study support the“assimilation capacity model”, rather than the“aerobic capacity model”of endothermy.