Year: 2008
Type: other
Abstract: Understanding the function of the “microcirculation” has played a central role in cardiovascular physiology since William Harvey first postulated that blood circulated through the “porosities of the lungs and flesh”. Although lacking the technology necessary to view the microvessels, Harvey predicted their existence to provide an explanation of how blood could pass from arterial to venous vessels, thus allowing continuous circulation through the cardiovascular system. His predictions were later verified by direct observation, first by Malpighi and later by the pioneering studies of Leeuwenhoek. Studies of the microcirculation remained a central focus of attention over the centuries as investigators worked to understand blood flow regulation, the exchange of materials between the flowing blood and the interstitial fluid and inflammation. Understanding of microvascular function was promoted by a number of exceptional scientists including Ernest Starling and August Krogh, who was awarded a Nobel Prize for his pioneering work. The microcirculation remains a central focus of interest in the cardiovascular system to this day. An outstanding and comprehensive review of the microcirculation was featured in Section 2, The Cardiovascular System, Volume IV, Part 2 of the Handbook of Physiology, published in 1984. More than two decades have passed since its publication, so it is timely to consider the need and usefulness of a revision. After careful consideration of the complex issues related to changes in information technology and research directions, it was concluded that revision of the microcirculation section of the Handbook would serve a very useful purpose, and would fill important gaps in the scientific literature. The advances in microvascular biology have proceeded at such a fast pace that compilation and analysis of information by any individual investigator is now a complex and demanding process. There is no other single source of material published today that provides an integrated evaluation of research developments in the field. This volume provides a printed repository of integrated information compiled and evaluated by experts in the field, enabling investigators to explore the significance of their findings in the context of other aspects of the microcirculation. In this way the new volume can have a direct role in helping to develop new pathways of research and scholarship. The magnitude of developments in this area, and the way in which the microcirculation relates to numerous areas of intense research activity today reflects the explosive growth in knowledge about the microcirculation. Microcirculatory biology is now a central discipline, providing a platform for studies in developmental biology, vascular pathology, and diabetic microangiopathy. Endothelial cell biology has become a central research area because of its role in angiogenesis, exchange of materials across vascular walls and inflammation. Our goal in developing this volume was to focus upon those areas in which the greatest change in understanding has occurred since publication of the previous volume. Areas of knowledge that have evolved or developed at a fast pace in the last 20 years include: biology of nitric oxide synthase (NOS), endothelial cell signaling, angiogenesis, cell adhesion molecules, lymphocyte trafficking, ion channels and receptors, propagated vasomotor responses, and an overall greater appreciation of the role of the microcirculation in inflammation and vascular disease. The contents are targeted to a wide professional audience including physiologists, graduate students, clinicians, medical residents and basic scientists from related fields. To achieve this goal, we have divided the materials in six sections, each subdivided into chapters that feature common themes and issues. The volume begins with an overview of the microcirculation to familiarize all readers with the terminology and techniques specific to examination of this component of the cardiovascular system. The first section focuses on fundamental microcirculatory processes. This begins with a description of rheology, with emphasis on the importance of network analysis, a subject that has gained considerable depth in the last few years. This section contains a chapter on endothelial cell biology, an area that has experienced a virtual explosion of new information during the last two decades. The biology and biochemical regulation of nitric oxide synthesis is presented in this section. Nitric oxide is a molecule that influences a number of microvascular functions and will therefore be addressed in multiple chapters throughout the book. Exchange across the microcirculation is also addressed in the first section. This chapter emphasizes recent advances in cellular regulation of microvascular exchange function and discusses inflammation and other factors that modulate this process. Finally, the microlymphatic biology is also presented in this section. The first section — because of its fundamental nature — serves to provide a background for the discussion of inflammation and other specific subjects that will occur in later chapters of the book. The second section of the book presents an analysis of the regulation of blood flow through the microcirculation. These chapters provide the general background necessary to understand specific aspects of blood flow regulation in a number of organs, and to understand how blood flow regulation is altered in the pathologic conditions dealt with in the last section of the book. The first chapter provides the latest information concerning the primary mechanisms involved in the regulation of vascular resistance and flow through the microcirculation. The second chapter deals with the way that neurotransmitters and circulating hormones influence the regulation of microvascular blood through interaction with their receptors on smooth muscle cells. The third section of the book addresses an area of microvascular function that has become the subject of increasing interest during the last two decades. This is the way in which the blood vessels adapt through changes in both morphology and function to the needs of the surrounding tissues during the process of angiogenesis. This chapter also provides a background to aid in the understanding of the changes that occur during the disease states addressed in the final section of the book. The fourth section of the book focuses upon the involvement of the microcirculation in immune function and inflammation. The intense interest in the contribution of white cells to ischemia/reperfusion injury and autoimmune diseases has created an enhanced interest in this area over the last decade. The chapter on inflammation deals directly with the participation of white cells in inflammatory responses, with focus upon the role of adhesion molecules in leukocyte rolling, adhesion and diapedesis. The second chapter in this section specifically covers the function of lymphocytes. The recent appreciation for the participation of lymphocytes in a wide variety of disease processes has also created intense interest in this area. The fifth section of the book addresses differences in microvascular function that exist among six important organs of the body. The goal of each of these chapters is to concentrate upon specific aspects of the microcirculation that represent adaptations of microvascular function in individual organs. Only organs in which significant advances have occurred in the last 20 years have been evaluated. Specific aspect of blood flow regulation, microvascular exchange, the effects of ischemia/reperfusion injury and specific involvement of the microcirculation in disease processes in these organs are addressed in these chapters. The sixth section of the book addresses three important disease processes in which alterations in microvascular function play a vital role and in which there has also been recent substantial advancement of our understanding of these processes. Although the primary goal of the Handbook is to present the latest advances in our understanding of the microcirculation, it is our hope that this volume will also serve to acknowledge the numerous outstanding contributions of the investigators that have preceded us in this fascinating area of investigation.
Source: Comprehensive physiology
Authors: Ronald F. Tuma, Walter N. Duran, Klaus Ley
Language: English
Subfield: Pulmonary and Respiratory Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W4212970294