RAPID: Oxygen management during flight in bar-headed geese

Meir Jessica U, La Jolla CA

Investigators

Abstract

The RAPID funding mechanism is used for proposals having severe urgency with regard to availability of, or access to data, facilities or specialized equipment. This award will support a six month time-urgent research project by Dr. Jessica U. Meir to study oxygen management during flight in the bar-headed goose, in collaboration with Dr. William K. Milson at the University of British Columbia in Canada. As the PI currently has a flock of imprinted bar-headed geese ready to fly and access to a suitable wind tunnel, the window of opportunity for these experiments is extremely limited (opening at the present time and closing within the next 6-8 months), and thus severe urgency is required in order to facilitate this research. As bar-headed geese are difficult to obtain and wind tunnels large enough to fly this species in are quite rare, the principal investigator is in a very unique position to obtain knowledge on this incredibly interesting species which has evolved specifically to maintain performance in hypoxia (low levels of oxygen in the body). During migration, the bar-headed goose flies from near-sea level in India, up over the Himalayas at altitudes of 6,000-9,000 meters to Tibet in a non-stop flight. In fact, they have been observed flying over Mount Everest. Oxygen levels at these altitudes are only ½ to 1/3 that at sea level, yet bar headed geese are able to perform continuous, strenuous exercise, with no allowance for acclimatization. Thus the bar headed goose represents an ideal model to investigate the physiological, cellular, and biochemical mechanisms of tolerance to hypoxia (low levels of oxygen in the body). It is hypothesized that mechanisms that maintain a sufficient O2 supply by optimizing O2 transport and delivery are the most important factors in this bird?s ability to sustain flight at altitudes where O2 is limited. This project aims to investigate the transport of O2 from the respiratory system to the tissue. The objectives of this project are to: 1) assess the ability of the heart to provide O2 to exercising tissues by obtaining continuous air sac, blood, and brain PO2 profiles in the bar-headed goose during flight in a wind tunnel in conditions of normoxia and hypoxia, using existing PO2 electrode technology, and 2) establish the relationships that exist between heart rate, oxygen consumption, and PO2 profiles during flight in a wind tunnel under conditions of both normoxia and hypoxia. It is hypothesized that: 1) regional PO2 values in bar-headed geese will reach lower levels than low altitude species during flight in hypoxia, and 2) the relationships between heart rate, oxygen consumption, and PO2 will be significantly different during flights in normoxia and hypoxia. A comprehensive calibration of the relationships of these parameters in the controlled setting of wind tunnel flight will allow for extrapolation to datasets consisting of heart rate only which have been obtained on bar-headed geese during their annual migrations in the wild. This project will also include: 1) the validation of a new, small and light PO2 recorder/microprocessor that will provide great potential for use on a variety of species and in clinical situations, 2) potential for application of findings to the field of human medicine (hypoxia and ischemia/reperfusion injury -- stroke, heart attack, etc.), 3) the creation of partnerships with international institutions and researchers, and finally, 4) the training and broadening of the skill-set of the young principal investigator. These studies will provide new knowledge into the adaptive mechanisms used by O2 tolerant species such as the bar-headed goose. Linking the natural biology of high altitude flight to clinically relevant models of hypoxic damage will ultimately allow us to identify therapeutic targets to enhance survival in humans after such circumstances as circulatory collapse, ischemic injury and other trauma states. The PI has also been extensively involved in educational and public outreach events, and is eager to continue in this vital role in the future.