Pulmonary blood flow distribution in standing horses is not dominated by gravity
العنوان: | Pulmonary blood flow distribution in standing horses is not dominated by gravity |
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المؤلفون: | M. J. Emery, Howard H. Erickson, Robb W. Glenny, Susan L. Bernard, Nayak L. Polissar, Rose M. McMurphy, Earl M. Gaughan, M. R. Fedde, Michael P. Hlastala |
المصدر: | Journal of Applied Physiology. 81:1051-1061 |
بيانات النشر: | American Physiological Society, 1996. |
سنة النشر: | 1996 |
مصطلحات موضوعية: | Pulmonary Circulation, Gravity (chemistry), Physiology, business.industry, Posture, Anatomy, Microsphere, Physiology (medical), Animals, Pulmonary blood flow, Distribution (pharmacology), Medicine, Horses, business, Perfusion, Blood Flow Velocity, Gravitation |
الوصف: | Recent studies using microspheres in dogs, pigs and goats have demonstrated considerable heterogeneity of pulmonary perfusion within isogravitational planes. These studies demonstrate a minimal role of gravity in determining pulmonary blood flow distribution. To test whether a gravitational gradient would be more apparent in an animal with large vertical lung height, we measured perfusion heterogeneity in horses (vertical lung height = approximately 55 cm). Four unanesthetized Thoroughbred geldings (422-500 kg) were studied awake in the standing position with fluorescent microspheres injected into a central vein. Between 1,621 and 2,503 pieces (1.3 cm3 in volume) were obtained from the lungs of each horse with spatial coordinates, and blood flow was determined for each piece. The coefficient of variation of blood flow throughout the lungs ranged between 22 and 57% among the horses. Considerable heterogeneity was seen in each isogravitational plane. The relationship between blood flow and vertical height up the lung was characterized by the slope and correlation coefficient of a least squares regression analysis. The slopes within each horse ranged from -0.052 to +0.021 relative flow units/cm height up the lung, and the correlation coefficients varied from 0.12 to 0.75. A positive slope, indicating that flow increased with vertical distance up the lung (opposite to gravity), was observed in three of the four horses. In addition, blood flow was uniformly low in three of the four horses in the most cranial portions of the lungs. We conclude that in lungs of resting unanesthetized horses, animals with a large lung height, there is no consistent vertical gradient to pulmonary blood flow and there is a considerable degree of perfusion heterogeneity, indicating that gravity alone does not play the major role in determining blood flow distribution. |
تدمد: | 1522-1601 8750-7587 |
URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::77828c13101e436a150bda1581d84515 https://doi.org/10.1152/jappl.1996.81.3.1051 |
رقم الأكسشن: | edsair.doi.dedup.....77828c13101e436a150bda1581d84515 |
قاعدة البيانات: | OpenAIRE |
تدمد: | 15221601 87507587 |
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