- 1.
Myocardial oxygen consumption (VOO2) was measured using an in situ, perfused heart preparation at 10°C. VOO2 increased in a linear fashion with power output when cardiac output (Vb) was elevated (volume loading). The increased VOO2 was possible through improved O2 delivery (increased Vb), but Δ POO2 (input POO2 - output POO2) was reduced. The mechanical efficiency of the heart was improved.
- 2.
VOO2 also increased in a linear fashion with power output when output pressure was increased with Vb constant (pressure loading). The increased VOO2 was supported by increased O2 removal from the perfusate since oxygen delivery (Vb and input POO2) was constant. Once more, improved mechanical efficiency was observed.
- 3.
VOO2 decreased as O2 delivery was reduced with progressive hypoxia. Even so, power output was maintained at a perfusate input POO2 of 81 Torr. Five of 11 hearts survived a 30-Torr POO2 exposure, but with a 29% decrease in power output and a 5-fold reduction in VOO2. The increase in the apparent aerobic efficiency which enabled this is discussed.
In the field: an interview with Sönke Johnsen
(update2)-SonkeJohnsen.jpg?versionId=3990)
Sönke Johnsen is a Professor at Duke University, USA, investigating visual ecology and he talks about his experiences of collecting transparent animals while blue water diving and in a submersible, as well as outrunning Hurricane Katrina.
Call for new preLighters
(update)-CallForPreLighters.png?versionId=3990)
preLights is the preprint highlighting community supported by The Company of Biologists. At the heart of preLights are our preLighters: early-career researchers who select and write about interesting new preprints for the research community. We are currently looking for new preLighters to join our team. Find out more and apply here.
Graham Scott in conversation with Big Biology
Graham Scott talks to Big Biology about the oxygen cascade in mice living on mountaintops, extreme environments for such small organisms. In this JEB-sponsored episode, they discuss the concept of symmorphosis and the evolution of the oxygen cascade.
Trap-jaw ants coordinate tendon and exoskeleton for perfect mandible arc
-AntJaws.png?versionId=3990)
Trap-jaw ants run the risk of tearing themselves apart when they fire off their mandibles, but Greg Sutton & co have discovered that the ants simultaneously push and pull the mandibles using energy stored in a head tendon and their exoskeleton to drive the jaws in a perfect arc.
Hearing without a tympanic ear
-Review.png?versionId=3990)
In their Review, Grace Capshaw, Jakob Christensen-Dalsgaard and Catherine Carr explore the mechanisms of hearing in extant atympanate vertebrates and the implications for the early evolution of tympanate hearing.
Social media
