Capillary blood transit time in muscles in relation to body size and aerobic capacity
| Autor: | S. R. Kayar, H. Hoppeler, J. H. Jones, K. Longworth, R. B. Armstrong, M. H. Laughlin, S. L. Lindstedt, J. E. P. W. Bicudo, K. Groebe, C. R. Taylor, E. R. Weibel |
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| Rok vydání: | 1994 |
| Předmět: |
Male
medicine.medical_specialty Cardiac output Physiology Physical Exertion Hemodynamics Foxes Rodentia Aquatic Science Biology Blood Circulation Time Dogs Oxygen Consumption Species Specificity Internal medicine medicine Animals Horses Treadmill Molecular Biology Ecology Evolution Behavior and Systematics Aerobic capacity Goats Muscles Horse VO2 max Blood flow Aerobiosis Capillaries Mitochondria Muscle Oxygen Endocrinology Insect Science Body Constitution Animal Science and Zoology Cattle Hemoglobin |
| Zdroj: | The Journal of experimental biology. 194 |
| ISSN: | 0022-0949 |
| Popis: | The mean minimal transit time for blood in muscle capillaries (tc) was estimated in six species, spanning two orders of magnitude in body mass and aerobic capacity: horse, steer, dog, goat, fox and agouti. Arterial and mixed venous blood O2 concentrations, blood hemoglobin concentrations ([Hb]) and oxygen uptake rates were measured while the animals ran on a treadmill at a speed that elicited the maximal oxygen consumption rate from each animal. Blood flow to the muscles (Q̇m) was assumed to be 85% of cardiac output, which was calculated using the Fick relationship. Total muscle capillary blood volume (Vc) and total muscle mitochondrial volume were estimated by morphometry, using a whole-body muscle sampling scheme. The tc was computed as Vc/Q̇m. The tc was 0.3–0.5 s in the 4 kg foxes and agoutis, 0.7–0.8 s in the 25 kg dogs and goats, and 0.8–1.0 s in the 400 kg horses and steers. The tc was positively correlated with body mass and negatively correlated with transcapillary O2 release rate per unit capillary length. Mitochondrial content was positively correlated with and with the product of Q̇m and [Hb]. These data suggested that Q̇m, Vc, maximal hemoglobin flux, and consequently tc, are co-adjusted to result in muscle O2 supply conditions that are matched to the O2 demands of the muscles at |
| Databáze: | OpenAIRE |
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