Skip to main content
PMC home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1970 May;208(1):65–83. doi: 10.1113/jphysiol.1970.sp009106

Cardiovascular function in young lambs during summit metabolism

G Alexander, D Williams
PMCID: PMC1348772  PMID: 5499779

Abstract

1. Cardiac output in lambs less than 3 days old was 50-100% higher during summit metabolism than during exposure to thermoneutral conditions.

2. The Fick method, based on oxygen consumption, and the dye dilution method for determination of cardiac output, gave qualitatively similar results, but there were considerable quantitative discrepancies.

3. The thermogenic tissues, muscle and brown fat, extracted some 80% of the oxygen from the blood perfusing them during summit metabolism.

4. Significant right to left shunts through the foramen ovale were detected in about half of the lambs during the first few days of life; the size and incidence of shunts decreased with advancing age but were apparently independent of environmental conditions.

5. During exposure to extreme cold, left to right shunts through the ductus arteriosus were detected in a high proportion of lambs, < 12 hr old, with detectable foramen ovale shunts. Pressure measurements in pulmonary and systemic arteries in very young lambs indicated that right to left shunting via the ductus was unlikely to occur; none was detected.

6. Summit metabolism was poorly related to oxygen carrying capacity of blood, but significant correlations of summit metabolism with cardiac output (positive) and with oxygen saturation of mixed venous blood (negative) were observed, though not consistently.

7. It is concluded that the great variability of summit metabolism between lambs older than 6 hr is not readily explained in terms of cardiovascular phenomena, but that the quantity and efficiency of thermogenic tissues probably play an important role in limiting summit metabolism.

Full text

PDF
68

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Alexander G., Williams D. Shivering and non-shivering therogenesis during summit metabolism in young lambs. J Physiol. 1968 Sep;198(2):251–276. doi: 10.1113/jphysiol.1968.sp008605. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Alexander G., Williams D. Summit metabolism and cardiovascular function in young lambs during hyperoxia and hypoxia. J Physiol. 1970 May;208(1):85–97. doi: 10.1113/jphysiol.1970.sp009107. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. CROSS K. W., DAWES G. S., MOTT J. C. Anoxia, oxygen consumption and cardiac output in new-born lambs and adult sheep. J Physiol. 1959 May 19;146(2):316–343. doi: 10.1113/jphysiol.1959.sp006195. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. DAWES G. S., MOTT J. C., WIDDICOMBE J. G. The patency of the ductus arteriosus in newborn lambs and its physiological consequences. J Physiol. 1955 May 27;128(2):361–383. doi: 10.1113/jphysiol.1955.sp005313. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. DEPOCAS F., HART J. S., HEROUX O. Energy metabolism of the white rat after acclimation to warm and cold environments. J Appl Physiol. 1957 May;10(3):393–397. doi: 10.1152/jappl.1957.10.3.393. [DOI] [PubMed] [Google Scholar]
  6. Douglas F. G., Becklake M. R. Effect of seasonal training on maximal cardiac output. J Appl Physiol. 1968 Nov;25(5):600–605. doi: 10.1152/jappl.1968.25.5.600. [DOI] [PubMed] [Google Scholar]
  7. Downing S. E., Rocamora J. M. Cardiovascular responses to hypoxemia and acidemia in the intact anesthetized lamb. Yale J Biol Med. 1968 Feb;40(4):296–312. [PMC free article] [PubMed] [Google Scholar]
  8. EMMANOUILIDES G. C., MOSS A. J., DUFFIE E. R., Jr, ADAMS F. H. PULMONARY ARTERIAL PRESSURE CHANGES IN HUMAN NEWBORN INFANTS FROM BIRTH TO 3 DAYS OF AGE. J Pediatr. 1964 Sep;65:327–333. doi: 10.1016/s0022-3476(64)80395-4. [DOI] [PubMed] [Google Scholar]
  9. HANSON J. S., TABAKIN B. S. SIMULTANEOUS AND RAPIDLY REPEATED CARDIAC OUTPUT DETERMINATIONS BY DYE-DILUTION METHOD. J Appl Physiol. 1964 Mar;19:275–278. doi: 10.1152/jappl.1964.19.2.275. [DOI] [PubMed] [Google Scholar]
  10. HERD J. A., BARGER A. C. SIMPLIFIED TECHNIQUE FOR CHRONIC CATHETERIZATION OF BLOOD VESSELS. J Appl Physiol. 1964 Jul;19:791–792. doi: 10.1152/jappl.1964.19.4.791. [DOI] [PubMed] [Google Scholar]
  11. Heim T., Hull D. The blood flow and oxygen consumption of brown adipose tissue in the new-born rabbit. J Physiol. 1966 Sep;186(1):42–55. doi: 10.1113/jphysiol.1966.sp008019. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Jansky L., Hart J. S. Cardiac output and organ blood flow in warm- and cold-acclimated rats exposed to cold. Can J Physiol Pharmacol. 1968 Jul;46(4):653–659. doi: 10.1139/y68-096. [DOI] [PubMed] [Google Scholar]
  13. POLOSA C., DAGIANTI A., GIULIANO G., CONDORELLI M. Valori tensivi del grande e del piccolo circolo in agnelli neonati. Boll Soc Ital Biol Sper. 1957 Oct-Nov;33(10-11):1593–1596. [PubMed] [Google Scholar]
  14. REEVES J. T., LEATHERS J. E. CIRCULATORY CHANGES FOLLOWING BIRTH OF THE CALF AND THE EFFECT OF HYPOXIA. Circ Res. 1964 Oct;15:343–354. doi: 10.1161/01.res.15.4.343. [DOI] [PubMed] [Google Scholar]
  15. RUDOLPH A. M., AULD P. A., GOLINKO R. J., PAUL M. H. Pulmonary vascular adjustments in the neonatal period. Pediatrics. 1961 Jul;28:28–34. [PubMed] [Google Scholar]
  16. STAHLMAN M. T., MERRILL R. E., LE QUIRE V. S. Cardiovascular adjustments in normal newborn lambs. Am J Dis Child. 1962 Oct;104:360–365. doi: 10.1001/archpedi.1962.02080030362007. [DOI] [PubMed] [Google Scholar]
  17. Thompson G. E., Moore R. E. A study of newborn rats exposed to the cold. Can J Physiol Pharmacol. 1968 Nov;46(6):865–871. doi: 10.1139/y68-135. [DOI] [PubMed] [Google Scholar]
  18. VEREL D., SAYNOR R., KESTEVEN A. B. A spectrophotometric method of estimating blood oxygen using the unicam SP 600. J Clin Pathol. 1960 Jul;13:361–363. doi: 10.1136/jcp.13.4.361. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES