Advancing Our Understanding of How Cardiovascular Control, Function and Plasticity Influence Fish Performance and Ecophysiology

心肺系统(鳃、心脏、血液、血管)对鱼类的生存至关重要，因为它确保向组织提供足够的氧气和营养。此外，重要的是线粒体(细胞的“发动机”)有效地利用这些营养物质和氧气，以便产生足够的能量来满足鱼类的需求(即使在紧张的条件下)。我的研究项目考察了不同鱼种/种群之间的代谢率、心脏功能、血管生理学、线粒体功能和应激生理学的差异，以及这如何使它们能够在具有挑战性的条件下生存；包括气候变化。虽然在过去的十年里，我们在了解鱼类的心肺功能及其与性能/生存的关系方面取得了巨大的进展，但这项研究留下了许多重要的问题没有得到解答。我和我的实习生(6名研究生和5名本科生，1名博士后)和我将在这笔助学金中解决其中的一些问题。鱼类心血管生理学的三个基本问题是：1)是什么因素决定了个体之间和物种之间最大心率和功能的差异？2)是什么限制了高温下的心脏功能？3)什么机制限制了鱼类随着温度变化增加每搏输出量(每次心跳的血流量)的能力。我们将解决所有这些问题。我实验室最近的研究还表明，暴露在低氧水平(低氧)下的鱼在暴露在高温下时无法提高心率，这使它们容易受到热浪的影响。因此，我们将进行几个实验来检验导致这种限制的生理和控制机制。此外，我们将调查鱼类从血液中提取氧气的能力和线粒体功能，是否分别是它们对严重低氧(低氧)条件和高温耐受性的关键决定因素。最后，我们将对非常微小的冠状血管(即对控制流向组织的血液最重要的微血管)以及鱼的性腺(卵巢和睾丸)中的类似血管进行多项研究。以前的研究是先前工作的继续，并且由于冠脉血流是应激条件下心脏性能的关键，所以进行这些研究是至关重要的。关于性腺血管的研究将被进行，因为流向这些器官的血液分别对卵子和精子的发育/质量(即产生下一代)非常重要，而关于冠状血管的数据可能不能反映温度或各种激素如何影响血管的扩张/收缩，从而影响其他组织的血液流动。总而言之，这项研究将极大地提高我们对鱼类心肺系统如何对急性和慢性应激源做出反应的知识，并将对鱼类管理和养护产生重要影响。

The cardiorespiratory system (gills, heart, blood, blood vessels) is critical to the survival of fish as it ensures adequate oxygen and nutrient delivery to the tissues. In addition, it is important that these nutrients and oxygen are used efficiently by mitochondria (the 'powerhouses' of cells) so that enough energy is produced to meet the fish's demands (even under stressful conditions). My research program examines how metabolic rate, heart function, blood vessel physiology, mitochondrial function and stress physiology differ between fish species/populations, and how this allows them to survive under challenging conditions; including climate change. While we have made tremendous progress in understanding fish cardiorespiratory function and its relationship to performance / survival over the past decade, this research has left many important questions unanswered. My trainees (6 graduate and 5 undergraduate students, and 1 post-doc) and I will address a number of these in this grant. Three fundamental questions in fish cardiovascular physiology are: 1) what factors determine between individual, and between species, differences in maximum heart rate and function?; 2) what limits heart function at high temperatures?; and 3) what mechanisms constrain the capacity of fishes to increase stroke volume (how much blood is pumped per heart beat) as temperatures change. We will address all of these questions. Recent studies in my lab have also shown that fish exposed to low oxygen levels (hypoxia) are unable to increase their heart rate when exposed to high temperatures, and that this makes them susceptible to heat waves. Thus, we will perform several experiments to examine the physiological and control mechanisms leading to this limitation. Further, we will investigate whether the capacity of the fish to extract oxygen from their blood, and mitochondrial function, are key determinants of how tolerant they are of severe hypoxic (low oxygen) conditions and high temperatures, respectively. Finally, we will conduct a number of studies on very small coronary vessels (i.e., microvessels, the ones that are most important in controlling blood flow to tissues), and similar vessels in the gonads (ovaries and testes) of fish. The former studies are a continuation of previous work, and are critical to perform as coronary blood flow is key to cardiac performance under stressful conditions. The studies on gonad vessels will be performed because blood flow to these organs is important for egg and sperm development / quality (i.e., producing the next generation), respectively, and data on coronary vessels may not reflect how temperature or various hormones affect vessel dilation/constriction, and thus blood flow, in other tissues. Collectively, this research will greatly enhance our knowledge of how the fish cardiorespiratory system responds to both acute and chronic stressors, and will have important implications for fish management and conservation.