Summary
Myocardial O2-extraction rate was studied during exercise induced augmentation of cardiac work in dogs.
The O2-extraction rate at rest was 75% of arterial content. Progressive levels of exercise increased the animals' O2-consumption from 7 ml/min · kg up to 91 ml/min · kg. Cardiac output rose from 108 ml/min · kg at rest to 484 ml/min · kg at the highest exercise level. The increase in myocardial O2-consumption from 9 ml/min·100 g at rest up to 57 ml/min·100 g at the highest exercise level was met by an increase in coronary flow from 59 to 256 ml/min·100 g and a rise of myocardial AVDO2 from 15 to 22 Vol%. Thus the latter contributed 40% to the augmented myocardial O2-requirements.
Coronary venous O2-saturation decreased to 9% saturation during highest levels of exercise. This low value was not the result of a limited coronary dilatory capacity, of inadequate state of exercise training, or of a relative underperfusion of the inner layers of the left ventricle.
Thus, augmentation of myocardial O2-extraction rate seems to be a mechanism of physiological relevance during exercise induced elevation of myocardial O2-requirements in dogs and may be explained by capillary recruitment in the myocardium.
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Ball, R. M., Bache, R. J., Cobb, F. R., Greenfield, J. C.: Regional myocardial blood flow during graded treadmill exercise in the dog. J. clin. Invest.55, 43–49 (1975)
Bretschneider, H. J., Frank, A., Kanzow, E., Bernhard, U.: Über den kritischen Wert und die physiologische Abhängigkeit der Sauerstoffsättigung des venösen Coronarblutes. Pflügers Arch.264, 399–423 (1957)
Buckberg, G. D., Kattus, A. A.: Factors determining the distribution and adequacy of left ventricular myocadial blood flow. Adv. exp. Med. Biol.39, 95–113 (1973)
Doll, E., Keul, J., Stein, H., Maiwald, C., Reindell, H.: Über den Stoffwechsel des menschlichen Herzens. II. Sauerstoff- und Kohlensäuredruck, pH, Standardbikarbonat und base excess im coronarvenösen Blut in Ruhe, während und nach körperlicher Arbeit. Pflügers Arch.282, 28–42 (1965)
Gregg, D. E., Khouri, E. M., Donald, D. E., Lowensohn, H. S., Pasyk, S.: Coronary circulation in the conscious dog with cardiac neural ablation. Circ. Res.31, 129–144 (1972)
Heiss, H. W., Barmeyer, J., Wink, K., Hell, G., Cerny, F. J., Keul, J., Reindell, H.: Studies on regulation of myocardial blood flow in man. 1. Training effects on blood flow and metabolism of healthy heart at rest and during standardized heavy exercise. Basic. Res. Cardiol.71, 658–675 (1976)
Henquell, L., Honig, C. R.: Intercapillary distance and capillary reserve in right and left ventricles: significance for control of tissue pO2. Microvasc. Res.12, 35–41 (1976)
Holtz, J., Bassenge, E., Restorff, W. v., Mayer, E.: Transmural differences in myocardial blood flow and in coronary dilatory capacity in hemodiluted conscious dogs. Basic Res. Cardiol.71, 36–46 (1976)
Holtz, J., Mayer, E., Bassenge, E.: Demonstration of α-adrenergic coronary control in different layers of cannine myocardium by regional myocardial sympathectomy. Pflügers Arch.372, 187–194 (1977)
Honig, C. R., Bourdeau-Martini, J.: Role of O2 in control of the coronary capillary reserve. Adv. exp. Med. Biol.39, 55–71 (1973)
Khouri, E. M., Gregg, D. E., Rayford, C. R.: Effect of exercise on cardiac output, left coronary flow and myocardial metabolism in the unanesthetized dog. Cir. Res.17, 427–437 (1965)
Lochner, W., Nasseri, M.: On venous oxygen pressure, regulation of coronary circulation and carbohydrate metabolism of the heart in muscular work. Pflügers Arch.269, 407–416 (1959)
Messner, J. V., Wagman, R. J., Levine, H. J., Neill, W. A., Krasnow, N., Gorlin, R.: Patterns of human myocardial oxygen extraction during rest and exercise. J. clin. Invest.41, 725–742 (1962)
Raff, W. K., Kosche, F., Lochner, W.: Herzfrequenz und extravasale Komponente des Coronarwiderstandes. Pflügers Arch.323, 241–249 (1971)
von Restorff, W., Bassenge, E.: Evaluation of a neurogenic rapid coronary dilatation during an excitatory response in conscious dogs. Pflügers Arch.367, 157–164 (1976)
von Restorff, W., Höfling, B., Holtz, J., Bassenge, E.: Effect of increased blood fluidity through hemodilution on coronary circulation at rest and during exercise in dogs. Pflügers Arch.357, 15–24 (1975)
von Restorff, W., Höfling, B., Holtz, J., Bassenge, E.: Effect of increased blood fluidity through hemodilution on general circulation at rest and during exercise. Pflügers Arch.357, 25–34 (1975)
Rubio, R., Berne, R. M.: Regulation of coronary blood flow. Progr. Cardiovasc. Diseases18, 105–122 (1975/76)
Vatner, S. F., Franklin, D., van Citters, R. L., Braunwald, E.: Effects of carotid sinus nerve stimulation on the coronary circulation of the conscious dog. Circ. Res.27, 11–21 (1970)
Vatner, S. F., Higgins, C. B., Millard, R. W., Franklin, D.: Role of the spleen in the peripheral vascular response to severe exercise in untethered dogs. Cardiovasc. Res.8, 276–282 (1974)
Wagner, J. A., Horvath, S. M., Dahms, T. E.: Cardiovascular, respiratory, and metabolic adjustments to exercise in dogs. J. Appl. Physiol.42, 403–407 (1977)
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von Restorff, W., Holtz, J. & Bassenge, E. Exercise induced augmentation of myocardial oxygen extraction in spite of normal coronary dilatory capacity in dogs. Pflugers Arch. 372, 181–185 (1977). https://doi.org/10.1007/BF00585334
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DOI: https://doi.org/10.1007/BF00585334