Volume 19, Number 4 (Part I), 1991 Printed in U S A .
TOXICOLOGIC PATHOLOGY 1SSN:O192-6233 Copyright O 1991 by the Society of Toxicologic Pathologists
Structure Function Correlates in the Pulmonary Vasculature During Acute Lung Injury and Chronic Pulmonary Hypertension*1,2 Center for Lung Research, Departments of Pathology and Medicine, Vanderbilt University Medical Center, MCN B- 1308, Nashville, Tennessee 37232-2650
Arteries, veins, and capillaries comprise the pulmonary vasculature. Three structural types of artery and vein are identified, the most muscular vessels being the largest. For example, arteries that accompany the preacinar arteries are muscular in structure while those within the acinus may be either, muscular, partially muscular or non-muscular. These small intra-acinar arteries contribute much to the hemodynamic behavior of the lung. Pulmonary edema results from damage to the capillary endothelium while chronic pulmonary hypertension is characterized by structural alterations in the pulmonary arteries. Correlation of the structural and functional changes of chronic pulmonary hypertension suggest that the increases in medial and adventitial thickness of the muscular preacinar arteries are secondary to the onset of this disease, while the changes in the peripheral arteries-appearance of muscle in smaller intra-acinar arteries than normal and reduction in arterial volume-contribute to the rise in pulmonary artery pressure and pulmonary vascular resistance. Such correlations of structure and hemodynamic measurements demand that the lung be fixed in a simple and standardized manner. Available methodology to evaluate the structural changes that occur during the development of pulmonary edema and chronic pulmonary hypertension are described. Keywords. Pulmonary artery; pulmonary vein; endotoxin; air embolization; pulmonary edema; rat; sheep
the development of chronic pulmonary hypertension. Correlations are also made between the structural changes and changes in pulmonary physiology. This last section relies heavily on data collected during our own studies and includes data from both rats and sheep. Endotoxemia will be used as a model of acute lung injury and continuous air embolization as a model for the pathogenesis of chronic pulmonary hypertension.
Two vascular systems supply blood to the lung: the bronchial circulation and the pulmonary circulation. The pulmonary circulation comprises, by far, the largest blood volume in the lung and, hence, is considered to contribute most to conservation of, and changes in, pulmonary vascular pathophysiology. This paper centers on the pulmonary circulation and falls into 3 main sections. The first section consists of a brief outline of the structure of the normal pulmonary circulation. This is followed by a short discussion of some of the methods currently available for preparing the lung for morphological examination. Finally, the paper covers some of the structural changes that occur during the onset of acute lung injury or pulmonary edema and during
STRUCTURE OF THE NORMAL PULMONARY CIRCULATION The pulmonary circulation falls, like that of any other organ, into 3 main compartments: arteries, veins, and capillaries. Three distinct structural types of artery and vein comprise the arterial and venous compartments: muscular, partially muscular, and non-muscular (24, 32). The following description concentrates on the structure of the pulmonary arteries but each structural type of vessel can also be found in the pulmonary venous circulation.
* Address correspondenceto: Dr. Barbara Meyrick, Center for Lung Research, Departments of Pathology and Medicine, Vanderbilt University Medical Center, MCN B- 1308, Nashville, Tennessee 37232-2650. I Presented at the Tenth International Symposium of the Society of Toxicologic Pathologists, "Pulmonary Toxicologic Pathology," June 2-6, 1991 in Monterey, California. Supported by grants from National Heart, Lung and Blood Institute, HL 191 53 and HL 34208.
Pulmonary Arteries The structure of an artery can be predicted by both its position in the lung and its external di447
TOXICOLOGIC PATHOLOGY 1SSN:O192-6233 Copyright O 1991 by the Society of Toxicologic Pathologists
Structure Function Correlates in the Pulmonary Vasculature During Acute Lung Injury and Chronic Pulmonary Hypertension*1,2 Center for Lung Research, Departments of Pathology and Medicine, Vanderbilt University Medical Center, MCN B- 1308, Nashville, Tennessee 37232-2650
Arteries, veins, and capillaries comprise the pulmonary vasculature. Three structural types of artery and vein are identified, the most muscular vessels being the largest. For example, arteries that accompany the preacinar arteries are muscular in structure while those within the acinus may be either, muscular, partially muscular or non-muscular. These small intra-acinar arteries contribute much to the hemodynamic behavior of the lung. Pulmonary edema results from damage to the capillary endothelium while chronic pulmonary hypertension is characterized by structural alterations in the pulmonary arteries. Correlation of the structural and functional changes of chronic pulmonary hypertension suggest that the increases in medial and adventitial thickness of the muscular preacinar arteries are secondary to the onset of this disease, while the changes in the peripheral arteries-appearance of muscle in smaller intra-acinar arteries than normal and reduction in arterial volume-contribute to the rise in pulmonary artery pressure and pulmonary vascular resistance. Such correlations of structure and hemodynamic measurements demand that the lung be fixed in a simple and standardized manner. Available methodology to evaluate the structural changes that occur during the development of pulmonary edema and chronic pulmonary hypertension are described. Keywords. Pulmonary artery; pulmonary vein; endotoxin; air embolization; pulmonary edema; rat; sheep
the development of chronic pulmonary hypertension. Correlations are also made between the structural changes and changes in pulmonary physiology. This last section relies heavily on data collected during our own studies and includes data from both rats and sheep. Endotoxemia will be used as a model of acute lung injury and continuous air embolization as a model for the pathogenesis of chronic pulmonary hypertension.
Two vascular systems supply blood to the lung: the bronchial circulation and the pulmonary circulation. The pulmonary circulation comprises, by far, the largest blood volume in the lung and, hence, is considered to contribute most to conservation of, and changes in, pulmonary vascular pathophysiology. This paper centers on the pulmonary circulation and falls into 3 main sections. The first section consists of a brief outline of the structure of the normal pulmonary circulation. This is followed by a short discussion of some of the methods currently available for preparing the lung for morphological examination. Finally, the paper covers some of the structural changes that occur during the onset of acute lung injury or pulmonary edema and during
STRUCTURE OF THE NORMAL PULMONARY CIRCULATION The pulmonary circulation falls, like that of any other organ, into 3 main compartments: arteries, veins, and capillaries. Three distinct structural types of artery and vein comprise the arterial and venous compartments: muscular, partially muscular, and non-muscular (24, 32). The following description concentrates on the structure of the pulmonary arteries but each structural type of vessel can also be found in the pulmonary venous circulation.
* Address correspondenceto: Dr. Barbara Meyrick, Center for Lung Research, Departments of Pathology and Medicine, Vanderbilt University Medical Center, MCN B- 1308, Nashville, Tennessee 37232-2650. I Presented at the Tenth International Symposium of the Society of Toxicologic Pathologists, "Pulmonary Toxicologic Pathology," June 2-6, 1991 in Monterey, California. Supported by grants from National Heart, Lung and Blood Institute, HL 191 53 and HL 34208.
Pulmonary Arteries The structure of an artery can be predicted by both its position in the lung and its external di447
