For hundreds of years, scientists have wondered why elephants can snorkel from considerable depths that would rupture the lungs of other mammals. Now, University of California, San Diego (UCSD) School of Medicine pulmonary physiologist John B. West, M.D., Ph.D., has explained the phenomenon.
In a presentation today at this year's meeting of the American Physiological Society in San Diego, West described his research findings in a lecture titled "Insights Into Respiratory Mechanisms: Lessons from the Elephant."
He noted that it is well known in Africa that elephants have peculiar lungs that allow them to move across lakes, completely submerged while they breathe through the tip of the trunk that protrudes just through the surface of the water. The pressure in the pleural membranes surrounding the lung is so great that the vessels should rupture or cause rapid edema in any other mammal. However, evolution has come up with a remarkable solution to this problem by replacing the normal pleural membranes in the elephant with sheets of dense connective tissue that allow the lungs to withstand the intense pressure.
"Many evolutionary biologists believe that the ancestors of the present day elephant were aquatic," West said. "It seems reasonable that the trunk which allows them to snorkel developed at that time."
He added that there is evidence that the elephant's closest living relatives are the manatee and dngong.
An intensely curious man, West's remarkable scientific career has taken him on many unique paths in his study of respiratory function. He was the first to take climbers up Mount Everest to study the effects of high altitude on oxygen. West designed NASA experiments that discovered the effects of gravity on the distribution of pulmonary blood flow, and he's developed a method to improve living conditions and work environment in those who live or work at high altitude.
"The different areas that I have pursued are all related to the function and the structure of the lung," West said. "Although they may seem to be very different, there are many close connections."
West was a member of Sir Edmund Hillary's Silver Hut expedition to the Himalayas in 1960-1961 when he lived for several months at an altitude of 19,000 feet (5800 meters). In 1981 he led the American Medical Research Expedition to Everest during which the first physiological measurements were made on the summit at 29,028 feet (8848 meters). His work on the effects of gravity in the lung led him into a study of weightlessness as it affects astronauts in space. Several experiments have been carried out in Spacelab on the Space Shuttle and on the International Space Station.
One of West's current projects is a highly promising technique to alleviate hypoxia in Cal Tech astronomers who work above 16,000 feet in northern Chile. This technique, in which the oxygen concentration of the rooms and laboratories is enriched with additional oxygen, is based on studies first conducted at the University of California's White Mountain Research Station.
"The Cal Tech astronomers are breathing 27% oxygen at an altitude of 5,000m (16,500 feet), in effect, lowering their altitude to a less-adverse 3,100 m (10,000 feet)," West noted. "The results are outstandingly good. Before, they had problems with memory, concentration and errors. Now, their work is almost as efficient as that at sea level."
Oxygen-enriched air may also be an option for a group of Chilean miners studied by West. They live at sea level and commute to copper mines located above 15,000 feet. The high altitude exposure has impaired the miners' sleep quality, mental performance, productivity and general well-being.
Source: University Of California - San Diego, September 3, 2002