Effects of Environmental Temperature on Cardio-Vascular System in Experimental Animals

为了阐明环境温度对实验动物心房钠素（ANP）的影响，采用生物遥测系统测量了热（33℃）和冷（15℃）环境条件下仓鼠、豚鼠和家兔的血压（BP）、心率（HR）和体温（BT）。采用免疫组化、电镜和放射免疫法检测两种环境下小鼠耳廓心肌细胞和血浆ANP水平。(1)平均动脉血压、HR、BT：低温条件下各物种的HR、BP、BT均无变化，但高温条件下豚鼠的BP较正常环境条件（22℃）显著降低。高温条件下，所有动物的HR没有变化，但BT在高温条件下显著高于对照水平。(2)血浆ANP浓度：高温条件下豚鼠血浆ANP浓度显著低于正常状态，而高温条件下仓鼠和家兔血浆ANP浓度无变化。在低温条件下，各树种的浓度变化不显著。(3)免疫组织化学和超微结构：高温24h豚鼠耳房心肌细胞ANP免疫反应性（IR）较正常条件弱，超微结构上，高温豚鼠心肌细胞ANP颗粒数量较正常条件少。热应激状态下仓鼠和家兔心肌细胞的IR和anp颗粒数量与正常状态相同。在低温条件下，各组心肌细胞IR和anp颗粒数量均无明显变化。本研究提示，高温环境对豚鼠循环ANP和心血管系统的影响较大。

To elucidate effects of environmental temperature on atrial natriuretic peptide (ANP) in experimental animals, the blood pressure (BP), heart rate (HR) and body temperature (BT) in hamsters, Guinea pigs, and rabbits under hot (33℃) and cold (l5℃) environmental conditions were measured by a biotelemetric system. Further, the ANP levels of auricular cardiocytes and plasma were examined by immunohistochemistry, electron microscopy, and radioimmunoassay in those animals under both environmental conditions. (1) Mean arterial BP, HR, BT : there was no change of HR, BP and BT in all species under cold condition, but BP of Guinea pig was significantly decreased in hot condition compared to the normal environmental condition (22℃). There was no change of HR in all species under hot condition, but BT in all animals was significantly increased under hot condition compared to the control level. (2) Plasma ANP concentration: the concentration of Guinea pig in hot condition was significantly lower than that in normal condition, but there was no change in the concentration of hamster and rabbit under hot condition. The concentration in all species under cold condition did not significantly change. (3) Immunohistochemistry and ultrastructure : ANP immunoreactivity (IR) in the auricular cardiocytes of Guinea pig after 24 hours under hot condition was weaker than that in normal condition, and ultrastructurally, the number of ANP-granules in the cardiocytes of' Guinea pig under hot condition was fewer than that in normal condition. The IR and the number of ANP-granules in the cardiocytes of hamster and rabbit under hot condition were the same level as normal condition. In cold condition, there were no changes in the IR and the number of ANP-granules of the cardiocytes in all species. The present study suggests that the circulating ANP and cardio-vascular systems in Guinea pig are greatly influenced by hot environmental condition.