... scope. Cardiac output was significantly elevated under hyperoxia at Ṁ O 2 ,max because of increased stroke volume, indicating that hyperoxia released a constraint on cardiac contractility apparent with normoxia. Thus, hyperoxia improved maximal cardiac performance, thereby enhancing tissue O 2 delivery...

...William Joyce; Tobias Wang ABSTRACT In the 1950s, Arthur C. Guyton removed the heart from its pedestal in cardiovascular physiology by arguing that cardiac output is primarily regulated by the peripheral vasculature. This is counterintuitive, as modulating heart rate would appear to be the most...

...William Joyce; Daniel W. White; Peter B. Raven; Tobias Wang ABSTRACT Vascular resistance and conductance are reciprocal indices of vascular tone that are often assumed to be interchangeable. However, in most animals in vivo , blood flow (i.e. cardiac output) typically varies much more than arterial...

... to the internal organs, and the stroke volume and cardiac output during the surface state. We then simulated breath-holding conditions and perfusion of the internal organs under the diving-induced bradycardia and reduction of stroke volume and cardiac output, using 10 beats min −1 as the limit for the heart rate...

... of Biologists Ltd 2018 http://www.biologists.com/user-licence-1-1/ Summary: Late stage snapping turtle embryos present increased oxygen carrying capacity and decreased cardiac output index and heart rate, which contribute to the reported patterns of turtle whole-egg V̇ O 2 . Cardiovascular...

... imposed activity. Chaenocephalus aceratus had a lower routine f H than N. coriiceps (9 beats min −1 versus 14 beats min −1 ) and a lower peak f H during acute warming (38 beats min −1 versus 55 beats min −1 ) with a similar cardiac breakpoint temperature (13 and 14°C, respectively). Routine cardiac output...

... to different functional outcomes of high-altitude adaptation. All species also appear to increase cardiac output in hypoxia, which would help ensure sufficient oxygen delivery from the lungs to the tissues, but our data suggest that there were different strategies for increasing cardiac output between...

... and heart rate ( f H ) before and after a ∼5% body mass meal. In adult N21 and H10 turtles, f H was increased significantly by feeding. Although total stroke volume ( V S,tot ) remained at fasted values, this tachycardia contributed to an elevation in total cardiac output ( ). However...

..., the blood-oxygen carrying capacity was higher than that of barnacle geese. Resting cardiac output also did not differ between groups and increased at least twofold during progressive hypoxia, initially as a result of increases in stroke volume. However, cardiac output increased at a higher F i O 2 threshold...

... pressures to calculate left ventricular wall stress. Cardiac output was also determined by inert gas rebreathing to provide an additional and independent estimate of stroke volume. Echocardiography and inert gas-rebreathing yielded similar cardiac outputs of 16.1±2.5 and 16.4±1.4 l min −1 , respectively...

.... hearts from 10°C fish cooled to 4°C, and hearts from 4°C fish measured at 10 and 0°C. Intrinsic heart rate ( f H ) decreased from 41 beats min −1 at 10°C to 33 beats min −1 at 4°C and 25 beats min −1 at 0°C. However, this degree of thermal dependency was not reflected in maximal cardiac output ( Q max...

... exceeding T opt , these findings offer a physiological explanation for the continuing success of this species throughout the current climate-warming period. Despite this, declining cardiac output was evident above 17°C, and maximum attainable swimming speed was impaired above ∼23°C, suggesting negative...

...). Morpholino knockdown of β2aAR had no effect on heart rate; however, stroke volume and cardiac output both increased significantly in one experiment but decreased significantly in another, a phenomenon which is not explainable using the current data set ( Table 2 ). β2bAR appears to play a more significant...

... the anoxic bradycardia, such that cardiac output decreased by only 33% from the routine value of 12.3±0.9 ml min –1 kg –1 . Cardiac power output decreased by only 25% from the routine value of 0.26±0.02 mW g –1 . During recovery from prolonged anoxia, cardiac output and heart rate increased to peak values...

... were restricted to males but included both nesting and non-nesting individuals to evaluate the cardiovascular performance of fish during parental care. Resting values for cardiac output ( ) and heart rate ( f H ) tended to be higher for nesting fish when adjusted for variation in temperature. Both...

... measured metabolic variables [routine oxygen consumption ( ), maximum , metabolic scope] and cardiac function (cardiac output, ; heart rate, f H ; and stroke volume, V S ) in these fish during critical swimming speed ( U crit ) tests performed at both levels of water oxygenation. Although surgery (flow...

... artery and hepatic portal vein, and to calculate cardiac output, heart rate and stroke volume. Fasted pythons while crawling experienced a 2.7- and 3.3-fold increase, respectively, in heart rate and cardiac output, and a 66% decrease in superior mesenteric flow. During the digestion of a rodent meal...

... for scientists who wish to make predictions on how climate change may influence animal distributions. [email protected] 19 8 2009 © 2009. 2009 thermal niches optimal temperature aerobic scope oxygen uptake metabolic rate cardiac output heart rate tissue oxygen extraction...

... and recovering sockeye salmon while water temperature was acutely increased from 15°C to 24°C in 2°C h –1 increments. Fish swam at a constant speed during the temperature change. By simultaneously measuring oxygen consumption( Ṁ O 2 ), cardiac output ( Q̇ ) and the blood oxygen status of arterial and venous...

.... This study examined the thermal plasticity of cardiac function in P. borchgrevinki to determine whether specialisation to stable low temperatures has led to the loss of the ability to acclimate physiological function. Fish were acclimated to–1°C and 4°C for 4–5 weeks and cardiac output was measured at rest...