Dr Takao Saruta in his laboratory of Keio University, called Jinken

Dr Takao Saruta, a great star of renin-angiotensin-aldosterone research and our much-admired teacher and leader, passed away at age 83 on September 20, 2023. On behalf of a lot of physicians and scientists who trained with Dr Saruta, we would like to express our deepest condolences to the Saruta families and are honored to present this article to celebrate Dr Saruta’s career and life story.

He is survived by his beloved wife Keiko and his two sons, Takayuki and Masayuki, both of whom are physicians. He was born in Tokyo, Japan, on November 29, 1939. His father, too, was a doctor who graduated from Keio University and worked at a hospital for wounded soldiers in Hadano, the outskirts of Tokyo during World War II. He remembers being chased by American Air Force Grumman fighter planes while attending that rural kindergarten. After the war ended, he and his two brothers commuted from Hadano to the heart of Tokyo, Hiroo, by taking the Odakyu Line to attend Keio’s elementary school, Yochisya. In Keio Junior High School and High School, he excelled in the archery club and in Keio University, he excelled in the tennis club. After graduating from Keio University School of Medicine in 1964, and then he completed 1-year internship at St. Luke’s International Hospital where Dr Shigeaki Hinohara was. In 1965, he entered Professor Seiichi Asano’s graduate school of Keio University School of Medicine. In 1969, he prepared a doctoral thesis on the study of the renin-angiotensin system in young hypertension.

He then went to the University of Texas, Texas, USA, from 1969 to 1971 to start his research regarding the renin-angiotensin-aldosterone system (RAAS) under the guidance of Professor Norman M. Kaplan. His American boss soon went on sabbatical in Boston, and he was able to use his research lab freely. His study abroad was very fruitful. He published two papers on aldosterone secretion regulation in JCI [1, 2], three papers on water immersion in the Journal of Applied Physiology with Dr Murray Epstein, in Miami [3,4,5] and one paper on oral contraception pill-related hypertension in the Archives of Internal Medicine [6]. After returning to Japan, he established his own laboratory and activity began his research on the RAAS and hypertension. Many young doctors joined his laboratory. At that time, it was not so common in Japan, but he presented his research findings at international conferences and promoted the creation of English-language papers. He and his wife, Keiko, treated the young research fellows and their wives to a feast at their home on New Year’s Day. This is likely something they experienced during their time studying in the USA.

In 1986, he became a Professor, Division of Nephrology, Endocrinology, and Metabolism, Department of Internal Medicine, Keio University, and then in 1991, he became the Vice Director of Keio University Hospital. In 1995, he became the Dean of the Medical School. During his tenure as the Dean of the Medical School for 6 years, he contributed to the construction of the research building for the Medical School. Subsequently, he became a Vice President at Keio University and continued to contribute to the further development of the medical school and hospital. During his current professorship, he continued to study the RAAS with his many disciples, and contributed to a lot of important clinical studies such as the Japanese Trial to Assess Optimal Systolic Blood Pressure in Elderly Hypertensive Patients (JATOS) [7]. His scientific accomplishments had wide range from renin to adrenocortical steroid hormones in the field of hypertension: renin and prorenin as endocrine factors [8], mechanisms of glucocorticoid-induced hypertension and Cushing syndrome [9, 10] and those of excessive aldosterone secretion in primary aldosteronism [11].

In 1990, he played a central role in the development of hypertension treatment guide by the Ministry of Health, Labour and Welfare and the Japan Medical Association. He also played a key role in the creation of hypertension treatment guidelines for the diagnosis and treatment of hypertension by the Japanese Society of Hypertension (JSH) in 2000 and 2004. He served as a president of the 18th Annual Scientific Meeting of the JSH in 1995, chairperson of the JSH from 1999 to 2002, a president of the 98th Scientific Meeting of the Japanese Society of Internal Medicine in 2001, and a Vice President of the 21st Scientific Meeting of the International Society of Hypertension in 2006. Immediately after retiring as a professor in 2005, he became Professor Emeritus of Keio University and continued the RAAS research with passion and social contributions to the Ministry of Education, Culture, Sports, Science and Technology, Japan, the Ministry of Health, Labour and Welfare, Japan, and the Consumer Affairs Agency, Japan. He was also a member of the Science Council of Japan from 2005 to 2008 and a collaborative member of the Science Council of Japan in 2008 and 2014.

His wife, Keiko, used to describe him as someone who is stubborn. We believe he is a man of conviction. He dedicated himself wholeheartedly to progress in all aspects of his research, his laboratory, the Department of Internal Medicine, Keio University, and medical research throughout Japan for over 50 years. We all miss Dr Takao Saruta and his extraordinary dedication to the research in the field of the renin-angiotensin-aldosterone system.