August and Marie Krogh and respiratory physiology

August and Marie Krogh first met in 1904 in the laboratory of Christian Bohr, a well-known Danish physiologist, where August was a teaching assistant and Marie Jørgensen a medical student. August, the oldest son of a brewer in Grenaa, Denmark, had recently obtained his doctorate for his work on respiration in frogs. Marie Jørgensen, the daughter of a farmer in Fyn, had at the age of six decided to pursue a medical career. August and Marie were married in 1905, and she joined him in some of his research. Christian Bohr was a staunch proponent of the theory that O2 was secreted across the lung epithelium. August Krogh at first set out to prove this hypothesis through precise and accurate measurements of gases in arterial blood and alveolar air with new apparatus he had constructed. Marie joined in this work, but the results they obtained did not support Bohr's hypothesis; to the contrary a series of very careful studies definitively proved that O2 is transported across the alveolar epithelium by diffusion alone. Due to the conflict with Bohr's views they delayed publication of the results until 1910. Marie Krogh, who finished her medical degree in 1907 and had begun a family, undertook an investigation of CO diffusion capacity through human lungs. This was to test if the rate of O2 diffusion was sufficient to account for the O2 uptake even at high altitudes or during various pulmonary diseases. Thirty-five years later the CO method, as described by Marie Krogh, was rediscovered and is now used extensively as a clinical test. August, in his continued studies of respiration in animals and humans, became interested in the delivery of O2 from the capillaries to the tissue. The studies that followed led to his discovery of the regulation of capillary circulation, for which he was awarded the Nobel Prize in 1920.