Determinants of Coronary Flow and Myocardial Metabolism in the Newborn Lamb. Influences of Hypoxia and Acidosis
Coronary blood flow and myocardial metabolism are subjects which have received intensive investigative interest since early in the present century (1). This work has been confined largely to the adults of many species, including man, while scant attention has been given to these problems in the newborn. In the early neonatal period there are major changes in cardiac output (2), in the distribution of blood flow (3) and in pressure relations within the various vascular compartments (4) associated with the transition to extrauterine life. Some of these changes may be reflected in the heart by a revision in the ratio of right to left ventricular weight from near unity at birth to one in which the left ventricle may weigh more than twice as much as the right at two to four weeks of age. Active myocardial growth is reflected in a remarkable increase in RNA synthetic processes which are most pronounced in the left ventricular myocardium (5).
KeywordsCardiac Output Coronary Sinus Coronary Flow Coronary Blood Flow Aortic Pressure
Unable to display preview. Download preview PDF.
- 1.Evans, C.L. and Matsuoka, Y.: The effect of various mechanical conditions on the gaseous metabolism and efficiency of the mammalian heart. Am. J. Physiol. 49: 378, 1915.Google Scholar
- 3.Rudolph, A.M. and Heymann, M.A.: Methods for studying distribution of blood flow, cardiac output and organ blood flow. Circ. Research, 21: 163, 1967.Google Scholar
- 4.Dawes, G.S.: Foetal and Neonatal Physiology. Year Book Med. Pub., Chicago, p. 162, 1968.Google Scholar
- 6.Downing, S.E., Talner, N.S., Campbell, A.G.M., Halloran, K.H. and Wax, H.B.: Influence of sympathetic nerve stimulation on ventricular function in the newborn lamb. Circ. Research 25: 417, 1969.Google Scholar
- 7.Roughton, F.J.W. and Scholander, P.F.: Micro gasometric estimation of the blood gases. J. Biol. Chem. 148: 541, 1943.Google Scholar
- 8.Barker, S.B. and Summerson, W.H.: The colorimetric deter¬mination of lactic acid in biological material. J. Biol. Chem. 138: 535, 1941.Google Scholar
- 9.Friedman, T. and Haugen, G.E.: Pyruvate acid: Determination of keto acids in blood and urine. J. Biol. Chem. 147: 415, 1943.Google Scholar
- 10.Altman, P.L. and Dittmer, D.S.: Respiration and Circulation. Federation of American Societies for Experimental Biology. Bethesda, Maryland, 232, 1971.Google Scholar
- 13.Starling, E.H. and Visscher, M.B.: The regulation of the energy output of the heart. J. Physiol (London) 62: 243, 1926.Google Scholar
- 14.Braunwald, E., Sarnoff, S.J., Case, R.B., Stainsby, W.N. and Welch, G.H., Jr.: Hemodynamic determinants of coronary flow; Effect of changes in aortic pressure and cardiac output on the relationship between myocardial oxygen consumption and coronary flow. Am. J. Physiol. 192 (3): 157, 1958.PubMedGoogle Scholar
- 18.Allella, A., Williams, F.L., Bolene-Williams, C. and Katz, L. N.: Inter-relation between cardiac oxygen consumption and coronary blood flow. Am. J. Physiol. 185: 570, 1955.Google Scholar