Cardiovascular suite for the imposition and assessment of physiological stressors

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Exercise is a common physiological stressor that affects multiple organ systems, providing a valuable model to study cardiovascular and other responses involved in homeostasis and adaptation in humans. Importantly, the ability of the heart to effectively pump blood can also be affected by other common stressors (e.g., heat, altitude, cannabis use) that can interact with the stresses imposed by exercise. Measuring cardiac output under these conditions is thus incredibly important for understanding normal exercise physiology and its applications to improving human life- from clinical applications to sport performance and military activities to space travel. However, measurements of cardiac output can be difficult to perform during intense exercise using standard imaging practices, and clinical alternatives are highly invasive or prohibitively expensive. This grant requests funds to purchase an inert gas rebreathe system to non-invasively measure cardiac output at rest and during exercise, and an environmental exercise chamber to study the effects of thermal and hypoxic stress and cannabis use on cardiovascular function during exercise. This equipment represents industry leading technologies that will fulfill a critical and urgent need in the applicants' research programs for 1) accurate and reliable measurements of cardiac output during exercise, and 2) examining the additional effects of common environmental stressors on cardiac output during exercise. Access to this equipment will support leading-edge NSERC-funded research and training programs at both U Guelph and McMaster. Dr. Burr's lab requires the equipment to follow-up on novel findings that blood flow restriction to the legs during exercise causes unexpected, and yet unexplained, augmentation of the ability to take up and use oxygen to perform muscular work. It will also advance research that shows sport- and environment-specific cardiac adaptations to exercise. Dr. Millar's group requires the inert gas rebreathing system to expand on important work understanding the sex differences in blood pressure response during exercise, and how blood pressure is modulated by differences in sympathetic control of vascular and cardiac output through differing intensities of exercise. The inert gas rebreathing system is also crucial to Dr. Gibala's work understanding how various exposures to exercise alter cardiac output, blood, and oxygen delivery to skeletal muscle. Finally, Drs Burr and Millar require both the enclosed chamber and the inert gas rebreathing device to support their pioneering and timely work examining the effects of cannabis on cardiovascular function during exercise. The applicants train a diverse group of 28 HQP who are currently hindered by a lack of access to this equipment. The requested items will greatly expand our research capacity and, including additional users, could positively benefit >50 HQP while supporting collaborative research across institutions.