This article is an obituary for Karl Artur Paul Edman, a professor emeritus of Pharmacology at Lund University who dedicated his life to muscle physiology research.
KAP Edman in 1992. Photo by Nancy Curtin. We announce, with great sadness, that Karl Artur Paul Edman (Paul), professor emeritus of Pharmacology at Lund University, Sweden, passed away on January 3, 2022 at the age of 95. He spent a life in science dedicated to muscle physiology. His work covered both skeletal muscle, heart and smooth muscle and included preparations ranging from isolated proteins, to single muscle fibers, and even whole organs. He addressed a wide spectrum of important problems related to both the excitation-contraction coupling and the perfection of actomyosin-based force production. Paul was born in 1926, in a rural area of the province of Småland, close to Kalmar on the southeast coast of Sweden. In the end of the 1940s, he moved to Uppsala to study medicine. In parallel with his medical studies, he started basic research in the lab of Ernest Barany, and published his first paper in 1950.1 While completing his medical training in 1955, Paul had already been captured by science and by the end of the 1950s he had defended his PhD thesis at the University of Uppsala and published 14 papers, half of them in Acta Physiologica Scandinavica. In these early studies of, for example, bivalent metal ions and ouabain effects on striated muscle, he used purified myosin and actin as well as glycerinated (skinned) muscle preparations, and he often talked about how he, during his first scientific meeting, was introduced to the latter preparation by the Nobel Laureate, Albert Szent-Gyorgi. After his PhD defense, Paul became a guest researcher with HO Schild at University College, London in 1960-1962 studying aspects of smooth muscle excitation-contraction coupling with publications in Nature and Journal of Physiology. Paul very much enjoyed his period in London where he, among other things, trained his English to a high degree of proficiency. He, for instance, mentioned how he, as soon as he encountered a new word, immediately looked it up. After moving back to Sweden and 2 years in Umeå, Paul took up a position in Pharmacology at University of Lund, his affiliation until his retirement in 1992. In the 1960s and 1970s, Paul´s research interests shifted back to striated muscle, with published work on both cardiac and skeletal muscle with several well-cited papers (eg Ref. 2), but from the end of the 1970s his main field of interest was skeletal muscle. The experimental preparation that became the focus of his attention was the single living skeletal muscle fiber from the frog. He developed his skills in dissecting such fibers in the mid-1960s, and they were central during a sabbatical visit to UCLA some years later. In this sabbatical, Paul (together with D Cleworth) pioneered the use of laser diffraction to follow sarcomere length changes in contracting striated muscle.3 He not only used to talk about this period with joy but also mentioned how he lost a single muscle fiber in an earthquake while dissecting. Sometimes he mentioned this when one of us had just lost a single fiber for more mundane reasons, possibly as some form of comfort that such things happen. The work of Paul Edman at UCLA was a starting point for his interest in the functional variability between different sarcomeres and neighboring segments along a single muscle fiber. He continued with more studies using laser diffraction but later turned to another technique, which allows observation of many individual short segments along the length of a muscle fiber.4-6 Black markers defined these segments that he detected by an optoelectronic device similar to the barcode readers used to read price tags. This experimental method bore the hallmark of Paul´s creativity and imagination. In addition to being a very careful, practically skilled and meticulous experimentalist, he designed smart methodological solutions “outside the box”. For instance, the black markers used to define the studied segments were pieces of dog´s hair generously donated by Paul´s favorite pet dog, Hector. Paul simply found that these markers had superior attachment properties without damaging the cell membrane. Because of his major interest in methodological innovation, Paul realized his need for input from a skilled engineer. Ove Höglund filled this role and collaborated with Paul in designing and building equipment for segment length measurement. They also designed and built advanced equipment for mechanical experiments on single muscle fibers, based on an analogic feed-back circuit to control fiber load and length, thus allowing detailed studies of the force-velocity relationship. The developments were key to several pioneering studies of the stretch response of active muscle7, 8 and of the force–velocity relationship for actively shortening muscle.9-11 Among other things, Paul´s studies provided evidence for a non-hyperbolic shape of the force-velocity relationship and reported several new phenomena in eccentric contraction. In the late 1970s he also developed an ingenious method,12 the slack test, to measure the unloaded shortening velocity of muscle without interference from series elastic elements. Upon Paul´s retirement in 1992, a symposium was held in his honor at University College London. Paul, however, continued the studies on single skeletal muscle fibers of the frog including further studies of muscle fatigue and characterization of the double hyperbolic shape of the force–velocity relationship.11, 13, 14 He also embarked on entirely new types of studies of the mechanics of muscle spindles15 and comparison of force–velocity relationships between intact frog and mammalian (mouse) fibers.16 This work, relying on the technical expertise of Britta Kronborg, was another example of Paul´s search for new challenges and his devotion to science. In this post-retirement period, Paul also further elucidated the excitation–contraction coupling, combining mechanical experiments with intracellular calcium measurements (eg. Ref. 17, 18). In his eighties and nineties, Paul was on the hunt for old computers to allow him to extract data from old experiments, stored on floppy disks. This hunt was successful, thanks primarily to Professor Anders Arner, and resulted in Paul's final paper in 2017 in Acta Physiologica,18 67 years after the first paper (in Acta Physiologica Scandinavica; predecessor of Acta Physiologica) and almost 10 years after his Jubilee doctorate (50 years of PhD) at Uppsala University. In his eighties, Paul´s achievements were celebrated by an honorary doctorate at University of Kalmar (now Linnaeus University), located in the town where Paul spent most of his pre-University education years. Paul was member of the Royal Physiographic Society of Lund and the Society awarded him The Thunberg Medal in 1992 for his work in muscle physiology. We who knew Paul from the early 1980s and onward enjoyed listening to his stories about his scientific life. Sometimes, these stories were taken as starting points to successfully encourage PhD students who had gone through some tough challenges in their project. Paul´s lab was also an inspirational gathering point for guests from all over the world, making it an excellent place, both to start and foster a scientific career. We thank Åke and Ruth Edman (Paul's son and daughter) and Anders Arner for the very helpful information they provided. An obituary for Paul Edman has been published in the Physiological Society’s on-line collection and can be down-loaded: https://www.physoc.org/explore-physiology/history/obituaries/k-a-paul-edman/.
Månsson et al. (Tue,) reported a other. This article is an obituary for Karl Artur Paul Edman, a professor emeritus of Pharmacology at Lund University who dedicated his life to muscle physiology research.