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Understanding the kidneys

Gerhard Malnic, a highly productive and influential scholar of renal physiology, inspired generations of researchers

The researcher in the lab in 2000

Carol Quintanilha

A not insignificant portion of the knowledge contained in current manuals on the kidney excretion mechanism is linked to Gerhard Malnic, one of the most important and prolific researchers of renal physiology in Brazil. A talented and creative researcher, Malnic was a professor at the Department of Physiology and Biophysics of the Institute of Biomedical Sciences at the University of São Paulo (USP). The physiologist died on February 25 at the age of 89. He dedicated his life almost entirely to research, training new scientists, teaching, and university administration.

Strictly speaking, the scientist never stopped working, despite taking compulsory retirement at the age of 70. Biochemist Hernan Chaimovich, professor emeritus at USP’s Institute of Chemistry, was always impressed by the strength and continuity of Malnic’s interest in science. “He started publishing articles in 1959 and continued publishing until 2022. That is an entire lifetime dedicated to understanding the kidneys. It’s extraordinary,” he says.

“Throughout his career, Malnic carried out research that had and still has a great influence on our understanding of how the kidneys work and the mechanism of action of drugs such as diuretics,” says nephrologist Roberto Zatz, a professor at USP’s School of Medicine (FM). He explains that in the 1960s, Malnic made decisive contributions to the explanation of two fundamental processes in the kidneys’ maintenance of chemical composition in mammals: “Regulation of urinary potassium excretion and mechanisms of urinary acid excretion.” Chaimovich emphasizes that this is important knowledge because it applies to drugs that regulate kidney performance and allow us to understand the impact of hormones on the organs’ physiological capacity to filter the blood and maintain the body’s acid-base and saline balance.

The son of an Austrian couple, Malnic was born in Milan in 1933. His father was a chemist who worked in the Italian textile industry before being hired by a German company to work in Brazil. During his childhood, Malnic wanted to follow the same profession as his father, who even set up a home laboratory for his son, where he began to develop the interest in experimentation that characterized his professional career.

His father, however, thought he would be better off studying medicine and convinced him to do so. Malnic began his studies at FM-USP in 1952. In the second year of his degree, he became interested in physiology and started working with laboratory research at the invitation of physiologist Alberto Carvalho da Silva (1916–2002), who was heavily involved in FAPESP as a member of the Board of Trustees, scientific director, and president of the Executive Board. He was granted Brazilian citizenship in 1956. He graduated in 1957, published his first paper two years later, and completed his doctorate in 1960. His PhD was supervised by Carvalho da Silva and focused on understanding the excretion mechanism of the kidneys, following Silva’s advice on the potential for new discoveries in the area.

Shortly after, at a conference in Buenos Aires, Malnic met one of the leading authorities in renal physiology at the time: American scientist Robert Franklin Pitts (1908–1977). Pitts invited him to join two of his students in the USA—coincidentally also Austrians—who were researching innovative techniques for micropuncturing rat kidneys. In 1961, Malnic received a grant from the Rockefeller Foundation to carry out postdoctoral research at Tulane University in New Orleans and Pitts’ laboratory at Cornell University, New York. Together with Gerhard Giebisch (1927–2020), who was one of the young Austrian researchers, Malnic improved the micropuncture techniques, allowing for discoveries about how potassium excretion occurs in the renal tubules.

His first papers to have a major impact were published during the time he was working as a researcher in the USA. In 1964, Malnic returned to Brazil with substantial experimental experience and a collection of lab equipment that he had been given so that he could continue his research and set up a lab at USP. Even with the proper equipment to perform micropunctures and take detailed measurements of potassium and sodium in rat kidneys, a great deal of manual skill and patience was needed. According to his colleagues, he had plenty of both. He loved carrying out experiments together with his students, and he did so until the end of his career.

His passion for the empirical side of science could only be compared to his love for music—he was a violinist in FM-USP’s amateur orchestra. His experiments in the lab were often accompanied by the sound of Mozart and Wagner. “The strongest image of Malnic in my mind is him working with his hands in the laboratory while listening to classical music on an old-fashioned record player,” says Chaimovich. It is an image commonly recalled by those who knew him.

Malnic developed new techniques and even built new research apparatus, as he described in a 2010 interview with Pesquisa FAPESP. Zatz explains that these innovations were fundamental to collecting the data that enabled the analysis of tiny amounts of fluid taken from microscopic kidney structures. These analyses, performed in the 1960s, led to studies on how the kidneys excrete acids, one of the processes Zatz cites as essential that were described by Malnic.

The physiologist also played an important role in the field of academic administration and science policy. He was president of the Brazilian Society of Biophysics and the Brazilian Society of Physiology. He also headed the Institute for Advanced Studies (IEA) at USP and the Federation of Experimental Biology Societies (FESBE).

Biochemist Walter Colli, professor emeritus at USP, says he frequently discussed science policy with Malnic. “He was a soft-spoken, gentle person, who never raised his voice,” Colli says. “He was neither aggressive nor submissive. He was quiet, but he always had something thoughtful to say.” Zatz saw him as an extremely approachable and affable man: “He was always available to guide his undergraduate and graduate students and answer their questions, and he always responded in a thoughtful and detailed manner.”

Chaimovich came to Brazil from his native Chile in 1969 and says that when he witnessed the arbitrary arrests and persecution of some of his USP colleagues, such as Isaias Raw (1927–2022) and Carvalho da Silva, he felt like going back. “But with Malnic, I felt less isolated here in Brazil,” he says. “In addition to our high-level scientific conversations, talking with him made me feel emotionally embraced. He was a person of immense kindness and generosity.”

“Malnic taught, inspired, and motivated many of us. He was an example of elegance and humility. A brilliant scientist who I was lucky to work with and learn from,” neuroscientist Luiz Eugênio Mello, scientific director of FAPESP, told Agência FAPESP.

Bettina Malnic, one of Gerhard’s daughters and now a professor of biochemistry at USP, highlights her father’s level of dedication to science: “For him, USP was not just his workplace—it was his home.” She says that her mother, Margot Petry Malnic (1935–2019), who was a professor of German at USP, used to joke that her husband was actually “married” to the university. She also says his friends joked that they knew when he was on vacation—because he would go to work wearing sneakers. In addition to Bettina, Malnic is survived by his daughter Beatriz, who is a singer, and three granddaughters.