Obituary Allyn L. Mark: a reflection by European, Canadian and Australian friends

Allyn L Mark, a prominent academic cardiologist and one of the most prestigious scientists of our time for the pathophysiology of hypertension and metabolic diseases, passed away on April 3rd, 2025 at the age of 89. He has been remembered for his important scientific achievements as well as for his open and generous personality by his colleagues from Iowa City, USA, where he spent most of his research, teaching and clinical working life. We would like to add to what has already been remembered few reminiscences of the impact of Allyn Mark to the research and professional growth of many investigators around the world, including us. Allyn was particularly close to European research. He astutely anticipated the novel insights into autonomic cardiovascular mechanisms and pathophysiology by the microneurographic recording of sympathetic nerve traffic in humans, originally developed by Gunnar Wallin and his colleagues in Uppsala, Sweden. After a sabbatical in Uppsala, Allyn spent time also in Milan at the Institute of Cardiovascular Research, then directed by Alberto Zanchetti, where he discussed several research projects, as a result of which in the following years Milanese investigators (Guido Grassi and Alberto Ferrari) went to work in Allyn's and colleagues’ laboratories in Iowa. For both, this was a period of critical importance either for the scientific value of the papers they published and for their growth to become intellectually independent investigators. In the year and a half he spent at the Iowa University under Allyn's guidance, Guido Grassi's papers clarified new important aspects of sympathetic nerve-related abnormalities in people with high blood pressure and cardiometabolic diseases, and his mastering of all aspects of the microneurographic technique allowed him to make it a fundamental research line during his entire carrier. During his repeated Iowa stages, between 1985 and 1989, Alberto Ferrari developed with Allyn and his group unique animal models of hypertension for defining the role of the autonomic nervous system on blood pressure control during the aging process, which led him to publish several important papers in experimental animals and humans until his premature death years later. Allyn's short time in Milan also set the basis for his cooperation with other investigators of the Institute, with one of which (Giuseppe Mancia) he later wrote the two chapters on the state-of-the-art of reflex control of the circulation in humans for the Handbook of Physiology, edited by the prestigious American Physiological Society. Allyn Mark's 2003 Irvine Page-Alva Bradley Lifetime Achievement Award of the Council for High Blood Pressure Research cited his “creative, mechanistic, influential, and often iconoclastic contributions to our understanding of the role of the sympathetic nervous system in physiological and pathological states in humans”. This approach to biomedical research has inspired all who had the privilege to train under his guidance, a large number indeed because Professor Allyn Mark's role as a mentor has involved, over his long working life at the Iowa University, a large number of clinicians and investigators. In addition to the Italian contingent, and limited to the signers of these notes, John Floras had the pleasure and privilege to train under Allyn's guidance during his post-doctoral research in humans (1984–1985), finalizing different major research projects, such as the neural contributions to post-exercise hypotension, the facilitation of neurogenic vasoconstriction by epinephrine and the modulation of cardiovascular reflexes by arginine vasopressin. Murray Esler worked with him on several research projects as well as on educational programs in the context of the activity of the High Blood Pressure Council. Finally, in his two years in Iowa (1996–1998), another European investigator, Kristoff Narkiewicz, worked with Allyn's group to elucidate what was at the time the first set of information on the neural pathophysiological component of the sleep apnoea syndrome, now a widespread research topic. For his outstanding scientific contributions, but also for his valuable interaction and role in the progress of European research on hypertension and metabolic disorders, Allyn was given in 2010 the prestigious Alberto Zanchetti Award for lifetime scientific achievements, an Award he received during the annual meeting of the European Society of Hypertension (ESH) in Milan. As properly emphasized by his colleagues, Allyn Mark was extremely brilliant in figuring out and seeking how to achieve integration of research data obtained by individual research lines. As mentioned in many of the important Awards he received, a special merit of Allyn was to anticipate how new data might translate into novel mechanistic-driven research, a stimulus to research creativity against the risk of falling into an easier more routine-like research practice. All of us remember his open and generous personality, ready to recognize the value and research achievements of his colleagues and to help those who had worked with him whom he always followed with interest beyond their time in Iowa. We will miss him greatly. Acknowledgements None. Conflicts of interest There are no conflicts of interest.