cardiovascular
- Activity, not submergence, explains diving heart rates of captive loggerhead sea turtles
Highlighted Article: Heart rates of undisturbed loggerhead sea turtles were not different whether turtles were submerged or out of water. Rather, heart rates changes were driven by turtles' activity level.
- Does the left aorta provide proton-rich blood to the gut when crocodilians digest a meal?
Summary: Blood in the left aorta of American alligators does not contain elevated PCO2 levels during digestion.
- 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.
- The caval sphincter in cetaceans and its predicted role in controlling venous flow during a dive
Summary: Locomotion may generate oscillations in a cetacean's venous system. Instead of using their caval sphincter to protect their heart from associated flow spurts, cetaceans could allow partial collapse of abdominal veins to smooth flow from the inferior vena cava.
- Controlling thoracic pressures in cetaceans during a breath-hold dive: importance of the diaphragm
Highlighted Article: Stiffening the cetacean diaphragm may stabilize thoracic pressures during a breath-hold dive but it could also cause pressure problems for some of the arteries.
- Autoregulation of cardiac output is overcome by adrenergic stimulation in the anaconda heart
Summary: Artificially elevating heart rate reduces stroke volume, leading to cardiac output ‘autoregulation’; adrenergic stimulation is needed to concurrently increase myocardial contractility to maintain stroke volume and increase cardiac output.
- In situ cardiac perfusion reveals interspecific variation of intraventricular flow separation in reptiles
Summary: Non-crocodilian reptiles have an undivided ventricle, but some (pythons, varanid lizards) robustly separate blood flow, whereas others (turtles, anacondas, bearded dragons) show a large capacity for cardiac shunting.