Schönweger G, Schwerte T, Pelster B
Institut für Zoologie und Limnologie, Universität A-6020 Innsbruck, Austria.
Am J Physiol Regul Integr Comp Physiol. 2000 Nov;279(5):R1634-40. doi: 10.1152/ajpregu.2000.279.5.R1634.
The minnow (Phoxinus phoxinus) was raised up to the stage of swim bladder inflation at temperatures between 10 degrees C and 25 degrees C, and the time of development significantly decreased at higher temperatures. Accordingly, initiation of cardiac activity was observed at day 2 in 25 degrees C animals and at day 4 in 12.5 degrees C animals. Only a minor increase in body mass was observed during the incubation period, and, at the end of the incubation period, animals raised at 25 degrees C did not have a significantly lower body mass compared with animals raised at 15 degrees C. Metabolic activity, determined as the rate of oxygen consumption of a larva, increased from 3.3 to 19.5 nmol/h during development at 15 degrees C and from 5.6 to 47.6 nmol/h during development at 25 degrees C. Heart rate showed a clear correlation to developmental stage as well as to developmental temperature, but at the onset of cardiac activity, diastolic ventricular volume and also stroke volume were higher at the lower temperatures. Furthermore, stroke volume increased with development, except for the group incubated at 12.5 degrees C, in which stroke volume decreased with development. Initial cardiac output showed no correlation to incubation temperature. Although metabolic activity increased severalfold during development from egg to the stage of swim bladder inflation at 15 degrees C and at 25 degrees C, weight-specific cardiac output increased only by approximately 40% with proceeding development. At 12.5 degrees C, cardiac output remained almost constant until opening of the swim bladder. The data support the notion that oxygen transport is not the major function of the circulatory system at this stage of development. The changes in heart rate with temperature appear to be due to the intrinsic properties of the pacemaker; there was no indication for a regulated response.
将米诺鱼（Phoxinus phoxinus）饲养在10摄氏度至25摄氏度的温度环境中，直至其鳔充气阶段，在较高温度下发育时间显著缩短。因此，在25摄氏度环境中的动物在第2天观察到心脏活动开始，而在12.5摄氏度环境中的动物在第4天观察到心脏活动开始。在孵化期仅观察到体重略有增加，并且在孵化期末，与在15摄氏度环境中饲养的动物相比，在25摄氏度环境中饲养的动物体重并无显著降低。以幼虫耗氧率确定的代谢活性，在15摄氏度发育期间从3.3纳摩尔/小时增加到19.5纳摩尔/小时，在25摄氏度发育期间从5.6纳摩尔/小时增加到47.6纳摩尔/小时。心率与发育阶段以及发育温度均呈现明显的相关性，但在心脏活动开始时，较低温度下舒张期心室容积以及每搏输出量更高。此外，除了在12.5摄氏度环境中孵化的组，其中每搏输出量随发育而降低外，每搏输出量随发育而增加。初始心输出量与孵化温度无关。尽管在15摄氏度和25摄氏度下从卵发育到鳔充气阶段期间代谢活性增加了数倍，但随着发育的进行，体重特异性心输出量仅增加了约40%。在12.5摄氏度时，直到鳔打开心输出量几乎保持恒定。这些数据支持了在发育的这个阶段氧气运输不是循环系统主要功能的观点。心率随温度的变化似乎是由于起搏器的内在特性；没有迹象表明存在调节反应。
