Circulation: A Comparison of Reptiles, Mammals, and Birds

  • F. N. White
Part of the Proceedings in Life Sciences book series (LIFE SCIENCES)

Summary

The evolution of endothermy has required structural elaboration of the airways and respiratory exchange surfaces. The presence of a completely septated heart in endotherms precludes the use of predominantly neurogenic control of pulmonary vascular resistance, as seen in noncrocodilian reptiles. The occurrence of ventilation-perfusion inequities in the finely subdivided airways of endotherms has required local vascular control in response to prevailing alveolar \({\text{P}}_{{\text{O}}_{\text{2}} }\) with potential for intrapulmonary shunting from poorly ventilated to more adequately ventilated respiratory units. No evidence for this mechanism is seen in the pulmonary circulation of turtles. Although mean air convection requirements are similar in reptiles and endotherms at similar body temperatures and mean blood flow requirements are similar when adjusted for differences in the O2 capacity of blood, many noncrocodilian reptiles exhibit temporal variation in pulmonary blood flow during a given respiratory cycle. Right-to-left intracardiac shunting is intensified with the length of the apneic period. Such shunts are not possible in endotherms because of complete cardiac septation. An hypothesis is presented to the effect that intracardiac shunting may aid in depletion of available O2 stores during protracted apnea. The shunt may profitably be viewed as a CO2 shunt past the alveolar gas phase. The resulting influence on alveolar and systemic P \({\text{P}}_{{\text{CO}}_{\text{2}} }\) may augment O2 binding to Hb in the lungs while intensifying unloading through the Bohr effect at the tissue level. From this perspective, the reptilian blood flow distribution patterns may be viewed as adaptive to the protracted apnea and lower respiratory frequency characterizing the group. These differences may be related to differences in metabolic intensity, respiratory frequency, and the consequent adaptive value of differing control mechanisms for pulmonary vascular resistance in ectotherms and endotherms.

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References

  1. 1.
    Bennett, A.F.: Blood physiology and oxygen transport during activity in two lizards, Varanus gouZdii and Sauromalus hispidus. Comp. Biochem. Physiol. 46A, 673–690 (1973)CrossRefGoogle Scholar
  2. 2.
    Berger, P.J.: The vagal and sympathetic innervation of the isolated pulmonary artery of a lizard and a tortoise. Comp. Gen. Pharmac. 3, 113–124 (1972)CrossRefGoogle Scholar
  3. 3.
    Burton, R.R., Besch, E.L., Smith, A.H.: Effect of chronic hypoxia on the pulmonary arterial blood pressure of the chicken. Am. J. Physiol. 214, 1438–1442 (1968)PubMedGoogle Scholar
  4. 4.
    Dejours, P.: Principles of Comparative Respiratory Physiology. Amsterdam, Oxford: North Holland, 1975, p. 253Google Scholar
  5. 5.
    Howell, B.J., Baumgardner, F.W., Bondi, K., Rahn, H.: Acid-base balance in cold-blooded vertebrates as a function of body temperature. Am. J. Physiol. 218, 600–606 (1970)PubMedGoogle Scholar
  6. 6.
    Jackson, D.C.: Metabolic depression and oxygen depletion in the diving turtle. J. App1. Physiol. 24, 503–509 (1968)Google Scholar
  7. 7.
    Jackson, D.C.: The effect of temperature on ventilation in the turtle, Pseudemys scripta slogans. Respir. Physiol. 12, 131–140 (1971)PubMedCrossRefGoogle Scholar
  8. 8.
    Kinney, J.L., Matsuura, D.T., White, F.N.: Cardiorespiratory effects of temperature in the turtle, Pseudemys floridana. Respir. Physiol. (in press)Google Scholar
  9. 9.
    Krogh, A.: Über vasomotorische Nerven zu den Lungen. Centralbl. Physiol. 20, 802–806 (1906)Google Scholar
  10. 10.
    Lenfant, C., Johansen, K., Petersen, J.A., Schmidt-Nielsen, K.: Respiration in the fresh water turtle, Chelys fimbriata. Respir. Physiol. 8, 261–275 (1970)PubMedCrossRefGoogle Scholar
  11. 11.
    Luckhardt, A.B., Carlson, A.J.: Studies on the visceral sensory nervous system. VII. On the presence of vasomotor fibers in the vagus nerve to the pulmonary vessels of the amphibian and the reptilian lung. Am. J. Physiol. 56, 72–112 (1921)Google Scholar
  12. 12.
    Millard, R.W., Johansen, K.: Ventricular outflow dynamics in the lizard, Varanus niloticus: Responses to hypoxia, hypercarbia and diving. J. Exp. Biol. 60, 871–880 (1974)PubMedGoogle Scholar
  13. 13.
    Millen, J.E., Murdaugh, H.V., Bauer, C.B., Robin, E.D.: Circulatory adaptations to diving in the fresh water turtle. Science 145, 591–593 (1964)PubMedCrossRefGoogle Scholar
  14. 14.
    Piiper, J., Drees, F., Scheid, P.: Gas exchange in the domestic fowl during spontaneous breathing and artigicial ventilation. Respir. Physiol. 9, 234–245 (1970)PubMedCrossRefGoogle Scholar
  15. 15.
    Romer, A.S.: Vertebrate Paleontology. 3rd ed. Chicago: Chicago Univ. Press, 1966, p. 468Google Scholar
  16. 16.
    Shelton, G., Burggren, W.: Cardiovascular dynamics of the Chelonia during apnoea and lung ventilation. J. Exp. Biol. 64, 323–343 (1976)PubMedGoogle Scholar
  17. 17.
    Southworth, F.C., Redfield, A.C.: The transport of gas by the blood of the turtle. J. Gen. Physiol. 9, 387–403 (1926)PubMedCrossRefGoogle Scholar
  18. 18.
    Steggerda, F.R., Essex, H.E.: Circulation and blood pressure in the great vessels and heart of the turtle (Chelydra serpentina). Am. J. Physiol. 190, 310–326 (1957)Google Scholar
  19. 19.
    Templeton, J.R.: Reptiles. In: Comparative Physiology of Thermoregulation, Vol. I. Whittow, G.C. (ed.). New York-London: Academic Press, 1970, pp. 167–221Google Scholar
  20. 20.
    Tenney, S.M., Remmers, J.E.: Comparative quantitative morphology of the mammalian lung: Diffusing area. Nature (London) 197, 54–56 (1963)CrossRefGoogle Scholar
  21. 21.
    Tenney, S.M., Tenney, J.B.: Quantitative morphology of cold-blooded lungs: Amphibia and Reptilia. Respir. Physiol. 9, 197–215 (1970)PubMedCrossRefGoogle Scholar
  22. 22.
    West, J.B.: Ventilation/blood flow and gas exchange. Oxford: Blackwell Scientific Publications, Ltd., 1970, p. 117Google Scholar
  23. 23.
    White, F.N.: Functional anatomy of the heart of reptiles. Am. Zool. 8, 211–219 (1968)PubMedGoogle Scholar
  24. 24.
    White, F.N.: Redistribution of cardiac output in the diving alligator. Copeia 3, 567–570 (1969)CrossRefGoogle Scholar
  25. 25.
    White, F.N.: Circulation. In: Biology of the Reptilia, Vol. V. Gans, C., Dawson, W.R. (eds.). London, New York, San Francisco: Academic Press, 1976, pp. 276–334Google Scholar
  26. 26.
    White, F.N.: Comparative aspects of vertebrate cardiorespiratory physiology. Ann. Rev. Physiol. (in press)Google Scholar
  27. 27.
    White, F.N., Kinney, J.: Ventilation-perfusion relationships in the turtle. Physiologist 19, 409 (1976)Google Scholar
  28. 28.
    White, F.N., Ross, G.: Blood flow in turtles. Nature (London) 208, 759 (1965)CrossRefGoogle Scholar
  29. 29.
    White, F.N., Ross, G.: Circulatory changes during experimental diving in the turtle. Am. J. Physiol. 211, 15–18 (1966)PubMedGoogle Scholar
  30. 30.
    Wilson, J.W.: Some physiological properties of reptilian blood. J. Cell. Comp. Physiol. 13, 315–326 (1939)CrossRefGoogle Scholar
  31. 31.
    Wood, S.C., Lenfant, C.J.M.: Respiration: Mechanics, control and gas exchange. In: Biology of the Reptilia, Vol. V. Gans, C., Dawson, W.R. (eds.). London, New York, San Francisco: Academic Press, 1976, pp. 225–274Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1978

Authors and Affiliations

  • F. N. White
    • 1
  1. 1.Physiological Research Laboratory, Scripps Institution of OceanographyUniversity of CaliforniaSan Diego, La JollaUSA

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