Mini Medical School
Breathing In Zero Gravity

INDIANAPOLIS -- Like the multiple branches of a large, sprawling tree, the arteries, capillaries and bronchioles in the lungs weave a beautiful and useful pattern. But, unlike a tree, the human system of branches is much more complicated and interdependent.

Halt blood flow to or from the lungs and the system can collapse. The same goes for oxygen.

"The body uses red blood cells to carry carbon dioxide to the capillaries in the lungs where it is exchanged for oxygen," explained Wiltz Wagner, Ph.D., during the March 6 session of Indiana University School of Medicine Mini Medical School. "Oxygenating the body through the cardiovascular system is the main function of the lungs."

Dr. Wagner, who is the V.K. Stoelting Professor of Anesthesia and a professor of physiology, biophysics and pediatrics at the IU School of Medicine, studies the mechanisms that control the human lungs.

The workhorse of the lung is air sacs called alveoli and more than 300 million of them are involved with the process of introducing oxygen into the body.

"The lung has to be stretchy, like a rubber glove," explained Dr. Wagner. "When you take a breath you stretch the rubber, and when you exhale the elastic tissue contracts. Inhaling creates negative pressure."

Diseases, such as black lung, or trauma, such as a puncture wound, reduce the elasticity so the lung cannot take in enough oxygen to support the body.

There is much that researchers understand about the physiology of the lung, but there is much that remains a mystery.

Dr. Wagner and a team of researchers, including Robb W. Glenny, MD, a physiology professor at the University of Washington, have dispelled the principle that blood flow in the lung is governed by only gravity. Instead, the researchers have shown pulmonary circulation is not solely dependent on gravity. Dr. Wagner said the tree-like structure of the lung's arterial circulatory system is another major determinant of how blood flows in the lungs.

Their initial findings were the result of a cooperative experiment with NASA in a jet appropriately named the "Vomit Comet." The plane, a KC-135, gives its passengers the experience of weightlessness at zero gravity with intermittent plunges toward Earth that create two times the force of gravity. Severe nausea is frequently the result. During several of these flights on which Dr. Wagner was a passenger, the researchers studied the effect of weightlessness on the lung's circulation in a pig.

Dr. Wagner and his team believe the study shows that gravity may account for only a minor portion of the blood flow in the lung and that the tree-like structure of the lung's circulatory system accounts for the remainder. This discordant finding remains a focus of Dr. Wagner's research.

The IU Medical Group and Indianapolis radio station WIBC sponsor Mini Medical School, which is offered by the Indiana University School of Medicine Faculty Community Relations Committee through the IUPUI Division of Continuing Studies.

For additional information see:
http://www.medicine.indiana.edu/iu_medicine/99_summer/pigsfly99.htm

Media Contact: Joe Stuteville
Tel: (317)274-7722
Email: jstutevi@iupui.edu

INDIANA UNIVERSITY
SCHOOL OF MEDICINE

MEDIA
RELATIONS

A STATEWIDE
RESOURCE

Phone
317 274 7722

Fax
317 278 8722