cardiac output
- Weighing the evidence for using vascular conductance, not resistance, in comparative cardiovascular physiology
Summary: Vascular conductance and resistance are reciprocal variables, but are not interchangeable terms. We argue that when blood flow changes by a greater relative magnitude than blood pressure, conductance yields a more faithful representation of cardiovascular status.
- Dynamics of blood circulation during diving in the bottlenose dolphin (Tursiops truncatus): the role of the retia mirabilia
Summary: A new hemodynamic model may clarify vascular dynamics in the diving bottlenose dolphin and explain the role of the retia mirabilia for the vascular supply to the brain.
- Convective oxygen transport during development in embryos of the snapping turtle Chelydra serpentina
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 V̇O2.
- Exploring nature's natural knockouts: in vivo cardiorespiratory performance of Antarctic fishes during acute warming
Summary: Routine cardiac output in the haemoglobinless icefish Chaenocephalus aceratus is lower than previously reported; they have a large cardiorespiratory scope during acute warming and activity, and show the same cardiac breakpoint temperature as the red-blooded Antarctic fish Notothenia coriiceps.
- Divergent respiratory and cardiovascular responses to hypoxia in bar-headed geese and Andean birds
Highlighted Article: When exposed to progressive hypoxia, bar-headed geese (biannual high-altitude migrators) increase ventilation and heart rate, whereas Andean geese (lifelong high-altitude residents) increase lung oxygen extraction and cardiac stroke volume.
- Embryonic hypoxia programmes postprandial cardiovascular function in adult common snapping turtles (Chelydra serpentina)
Summary: During embryonic development in underground nests, reptiles routinely experience hypoxia, which programmes cardiovascular physiology into adulthood, dictating convective transport during periods of elevated oxygen demand.
- Altitude matters: differences in cardiovascular and respiratory responses to hypoxia in bar-headed geese reared at high and low altitudes
Highlighted Article: When exposed to progressive hypoxia, bar-headed geese reared at altitude exhibit a reduced metabolism and modestly increased ventilatory response, and also initiated cardiac responses earlier than geese reared at low altitude.
- The thick left ventricular wall of the giraffe heart normalises wall tension, but limits stroke volume and cardiac output
Summary: A left ventricular cavity and low stroke volume characterise the giraffe heart, resulting in typical mammalian left ventricular wall tensions but lowered cardiac output.