Porter E S, Gamperl A K
Department of Ocean Sciences, Memorial University of Newfoundland and Labrador, St. John's, NL, A1C 5S7, Canada.
J Comp Physiol B. 2025 Apr;195(2):173-179. doi: 10.1007/s00360-024-01600-1. Epub 2025 Jan 7.
We developed and validated a surgical technique to measure central venous pressure (CVP) in Nile tilapia, and investigated the effects of an acute temperature decrease (from 30 vs. 24 °C) and changes in heart rate (f) using zatebradine hydrocholoride, which decreases intrinsic f on this species' cardiac function. As predicted, f and cardiac output ( ) were ~ 40% lower in the acutely cooled fish, and both groups had very comparable (i.e., within 10%) values for stroke volume (V) The CVP of fish acutely exposed to 24 °C was consistently ~ 0.04 kPa higher than in those measured at 30 °C across all concentrations of zatebradine (i.e., CVP increased from 0.04 to 0.11 kPa vs. - 0.01-0.07 kPa for 24 vs. 30 °C tilapia, respectively, as f was reduced). However, this did not result in an increase in V due to a right-shifted relationship between CVP and V for the 24 °C fish. These data suggest that the V of tilapia is less sensitive to changes/increases in CVP when temperature is acutely lowered, and that regardless of increases in preload (CVP), is primarily modulated by f in this species.
我们开发并验证了一种用于测量尼罗罗非鱼中心静脉压（CVP）的手术技术，并使用盐酸扎替雷定研究了急性降温（从30℃降至24℃）和心率（f）变化对该物种心脏功能的影响，盐酸扎替雷定可降低其固有心率。正如预期的那样，急性降温的鱼的心率和心输出量（ ）降低了约40%，两组的每搏输出量（V）值非常接近（即相差10%以内）。在所有浓度的盐酸扎替雷定作用下，急性暴露于24℃的鱼的中心静脉压始终比在30℃下测量的鱼高约0.04kPa（即24℃罗非鱼的中心静脉压从0.04kPa增加到0.11kPa，而30℃罗非鱼的中心静脉压为-0.01 - 0.07kPa，此时心率降低）。然而，由于24℃鱼的中心静脉压与每搏输出量之间的关系右移，这并未导致每搏输出量增加。这些数据表明，当温度急性降低时，罗非鱼的每搏输出量对中心静脉压的变化/升高不太敏感，并且在该物种中，无论前负荷（中心静脉压）如何增加，心输出量主要由心率调节。
