The Physiologist


Bodil Schmidt-Nielsen (1918-2015) 48th APS President

William H. Dantzler

 Bodil Schmidt-Nielsen

Bodil Schmidt-Nielsen, an eminent renal and comparative physiologist and the 48th President of the American Physiological Society, passed away peacefully on the night of April 27, 2015. She was 96.

During a long career, Bodil Schmidt-Nielsen carried out many significant studies on fluid and electrolyte balance and nitrogen excretion in mammalian and nonmammalian vertebrates. The studies that first brought her national and international attention involved fluid balance in kangaroo rats, pocket mice, and wood rats in southern Arizona, performed with her first husband, Knut Schmidt-Nielsen, during the summers of 1947 and 1948. These studies were remarkable in their completeness and set a new standard for understanding water balance in animals living in diverse environments. These and later studies on camels in the Sahara Desert formed the basis for her Bowditch Award Lecture for the American Physiological Society (of which she was the second recipient) in 1957.

Of particular significance for her later scientific career, the early studies on kangaroo rats led to her enduring interest in renal function and a series of studies on the mechanisms involved in urea excretion and their possible contribution to the mammalian urine concentrating mechanism. These later studies had a significant impact on our understanding of mammalian renal function. They also led to her meeting with Homer Smith and an invitation to spend the summer of 1952 at the Mount Desert Island Biological Laboratory (MDIBL) in Maine, thus beginning her long association with that laboratory.

In a series of brilliantly conceived clearance and tissue studies on kangaroo rats and laboratory rats, she provided evidence first for carrier-mediated urea reabsorption by the renal tubules and second for both active urea reabsorption and urea secretion by the renal tubules under certain circumstances. At the time, the scientific community was unaccepting of her data and her conclusions. However, in recent years, studies on mammalian renal inner medullary collecting ducts with newer physiological techniques and molecular techniques have shown that she was largely correct.

Schmidt-Nielsen's studies on urea excretion in a number of mammalian species led to an increased understanding of the way in which it accumulates in the inner medulla and contributes to the osmotic gradient in that region. Although the mechanism by which this osmotic gradient is established remains a mystery to this day, Schmidt-Nielsen's studies on the significance of urea formed the basis for a number of theoretical models for the inner medullary concentrating process. In addition, in the final years of her active research career, she demonstrated the importance of the peristaltic contractions of the intact renal pelvis on the flow of fluid in the inner medullary blood vessels and renal tubules, and on the size of the cells and intercellular spaces. She suggested ways in which these effects might contribute to the development of the osmotic gradient, an idea that has been expanded and extended by other scientists. Although there is no experimental data to support any exact model relative to the pelvic contractions and it is not clear how large an effect this would have on the overall urine concentrating process, Schmidt-Nielsen's research certainly continues to have a significant influence on thinking in this area.

Schmidt-Nielsen was born on November 3, 1918, in Copenhagen, Denmark, the youngest of four children of two other eminent physiologists, the Nobel Laureate August Krogh and Marie Krogh. Throughout her childhood and youth, she was regularly exposed to her parents' discussions of the research problems of the day. Although originally considering medicine as a career, she instead chose to enter the School of Dentistry at the University of Copenhagen, from which she received her Doctor of Dental Surgery degree in 1941. It was during her dental studies that she became especially intrigued by physiology and performed her first physiological research on the exchange of calcium and phosphorus in teeth. She continued studies on calcium and phosphorus metabolism in the School of Dentistry during World War II, but even then began to consider wider studies on fluid and ion balance. She received her Doctor of Odontology degree in 1946 and her Doctor of Philosophy degree in 1955, both from the University of Copenhagen.

Schmidt-Nielsen came to the United States in 1946. Initially, she was a research associate at Swarthmore College (1946-1948), Stanford (1948-1949), Cincinnati (1949-1952), and Duke (1952-1957). She then served as an associate research professor at Duke (first in Zoology and then in Zoology and Physiology) from 1957 to 1964, when she left to become Professor of Biology at Case Western Reserve University. However, in 1971, after a year as chair of the department, she resigned her tenured professorship there to become the first permanent research scientist at MDIBL because, as she stated, "I wanted to spend all of my time on research rather than administrative duties." She retained this position at MDIBL until 1986, when she closed her active research laboratory. However, she continued to be present at MDIBL during the summers, contributing to research discussions, and until 1997 held an adjunct appointment in the Physiology Department at the University of Florida, where she spent her winters.

Schmidt-Nielsen was very active in the American Physiological Society, serving as a member of Council and, in 1975-1976, as the Society's 48th President. She was the Society's first and, for the next 28 years, only woman president. In addition to the Bowditch Award Lectureship of the Society in 1957, she was awarded the first August Krogh Distinguished Lectureship by the Comparative and Evolutionary Physiology Section of APS in 1994 and the Robert W. Berliner Award for excellence in renal physiology research by the Renal Section of APS in 1998. For her contributions to physiology and her service to the American Physiological Society, she received the Ray G. Daggs Award from the Society in 1989.

Over the years, Schmidt-Nielsen received many other honors acknowledging her contributions to physiological research. These include election as a Fellow of the New York Academy of Sciences (1958), AAAS (1959), and the American Academy of Arts and Sciences (1973). She was also a Guggenheim Fellow (1953-1954), Established Investigator of the American Heart Association (1954-1962), and Career Awardee of the National Institutes of Health (1962-1964). She received an honorary DSc from Bates College in Lewiston, Maine in 1983 and an honorary MD from Aarhus University in Denmark in 1997.

Schmidt-Nielsen married Knut Schmidt-Nielsen in 1939, with whom she had three children, Astrid, Bent, and Mimi. This marriage ended in divorce in 1966. In 1968, she married Roger G. Chagnon, who passed away in 2003. She is survived by two of her children, Astrid and Bent (Mimi passed away in 1984), four grandchildren (Mimi, Tom, Erik, and Peter), four great grandchildren, and two great-great granddaughters.

In December 2005, Bodil Schmidt-Nielsen established a charitable remainder trust through the APS, naming the Society as the beneficiary. A charitable remainder trust is a gift that provides fixed retirement income to an individual for life, after which the remaining assets go to the chosen beneficiary. The APS will use this gift to partially fund an endowment for the Bodil M. Schmidt-Nielsen Distinguished Mentor and Scientist Award, which recognizes APS members who have made outstanding contributions to physiological research and have also demonstrated dedication and commitment to excellence in training of young physiologists.

The Society's goal is to fully endow the award by creating a $100,000 endowment fund. With Schmidt- Nielsen's gift, the goal is over 60% complete. In addition, to honor Schmidt-Nielsen for her generous gift, the APS inducted her into the newly created 1887 Legacy Circle. Details on membership in the 1887 Legacy Circle will be forthcoming in the next several weeks on our new APS Giving website ( If you would like to honor Bodil Schmidt-Nielsen yourself, please consider making a $500 gift to the Bodil Schmidt-Nielsen Fund to preserve the Bodil Schmidt-Nielsen Distinguished Mentor and Scientist Award in perpetuity (