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，因为它确保向组织输送足够的氧气和营养。此外，重要的是这些营养物质和氧气被线粒体（细胞的“发电站”）有效地利用，以便产生足够的能量来满足鱼的需求（即使在压力条件下）。我的研究项目研究了鱼类物种/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。虽然在过去的十年中，我们在了解鱼类心肺功能及其与性能/生存的关系方面取得了巨大进展，但这项研究仍然留下了许多重要的问题没有答案。我的学员（6名研究生和5名本科生，以及1名博士后）和我将在这笔赠款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)在高温下是什么限制了心脏功能？以及3）当温度变化时，什么机制限制了鱼类增加每搏输出量（每次心跳泵出多少血液）的能力。我们将解决所有这些问题。 我实验室最近的研究也表明，暴露在低氧水平（缺氧）的鱼类在暴露于高温时无法增加心率，这使得它们容易受到热浪的影响。因此，我们将进行几个实验来检查导致这种限制的生理和控制机制。此外，我们将研究鱼从血液中提取氧气的能力和线粒体功能是否是它们分别耐受严重缺氧（低氧）条件和高温的关键决定因素。最后，我们将对非常小的冠状动脉血管（即，微血管，在控制血液流向组织中最重要的微血管），以及鱼类性腺（卵巢和睾丸）中的类似血管。以前的研究是以前工作的延续，并且对于在压力条件下进行冠状动脉血流是心脏性能的关键。将对性腺血管进行研究，因为流向这些器官的血流对卵子和精子发育/质量很重要（即，产生下一代），并且冠状血管的数据可能无法反映温度或各种激素如何影响血管扩张/收缩，从而影响其他组织中的血流。 总的来说，这项研究将大大提高我们对鱼类心肺系统如何应对急性和慢性应激源的认识，并将对鱼类管理和保护产生重要影响。

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.