Novel mechanisms in the regulation of coronary circulation - in memoriam of Professor Alexander Juhász-Nagy

Prof. Dr. Ákos Koller started his medical training in 1969, at The University of Szeged. In 1970, he transferred to the Budapest Medical School, now Semmelweis University. After finishing the University, he started to work in the legendary department of Arisztid Kovach, the Clinical Experimental Department and 2nd Department of Physiology. Then, between 1982 and 1985 he conducted research at the Department of Physiology of the University of Arizona with Prof. Paul Johnson. From 1987 has been in a continuing collaboration with Prof. Gabor Kaley at the Department of Physiology at New York Medical College, USA. In the meantime, he had appointments at the Department of Pathophysiology at Semmelweis University from 1996 andsince 2008 at the Department of Pathophysiology and Gerontology at University of Pécs. The topics of his investigation include the microcirculation, role of endothelium in mechanotransduction and vascular biology in normal and disease conditions. In 2005 he founded the Hungarian Society for Microcirculation and Vascular Biology. Since 2006, he is the president of the European Society for Microcirculation

Abstract

Previously it has been established that local mechanisms – independent of neural and humoral pathways - are important determinants of coronary blood flow. Changes in the metabolism of cardiac tissue during increased demand and/or ischemia elicit changes in coronary blood flow. This, the so called metabolic regulation of coronary blood flow, was supported by the tight correlation between cardiac performance/oxygen consumption and coronary blood flow. The work of Professor Alexander Juhász-Nagy greatly contributed to the development of this idea.The very special aspect of coronary circulation is that hemodynamic forces change substantially during each cardiac cycle. This fact initiated studies to elucidate the role of intraluminal pressure and wall shear stress sensitive mechanisms in regulation of microvascular tone. Whereas, the myogenic mechanism is thought to play role in the autoregulation of coronary blood flow ,the shear stress sensitive mechanism is important to regulate circulatory energy loss when flow increases. These local mechanisms are thought to provide tight coupling between cardiac metabolism and blood flow. It has been shown that besides regulating coronary microvasculartone, nitric oxide (NO), released to increases in shear stress, exerts direct effects on cardiac muscle, such as the modulation of substrate (energy) metabolism. Impaired availability of endothelium derived NO, assumed to be the cause of microvascular disease, should also be considered a contributor of cardiac dysfunction.