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AGE

, 15:1 | Cite as

Effects of aging on cutaneous regional and superficial capillary blood flows during heat stress in the rat

  • Kathleen A. Westphal
  • Daniel R. Richardson
Article

Abstract

The purpose of this study was to investigate the effects of aging on the cutaneous circulatory response to heat stress. Young (6–8 too) and old (22–24 mo) Fischer 344 rats were placed unanesthetized in an environmental chamber arranged so that the body could be heated while the tail remained at ambient temperature (23°C Total blood flow (TBF) to the tail was measured via strain gauge plethysmography while the cutaneous microcirculation was investigated by way of videomicroscopic measurements of capillary blood cell velocity (CBV) and the density of flow active capillaries (DFC) within the subepidermal vascular plexus of the tail. The measurements of CBV were multiplied by vessel cross sectional area and DFC to obtain a calculated variable termed the capillary perfusion index (CPI). As chamber temperature was increased in a stepwise manner from 23° to 40°C TBF and CPI significantly increased in both young and old animals (P≤0.001) with the rise in CPI being mediated by changes in both CBV and DFC. Colonic temperature (Tc) tended to be lower in the old group up to a chamber temperature of 40°C at which point the old animals had a higher Tc. At the initial chamber temperature of 23°C the CPI/TBF ratio was significantly higher in the old compared to the young rats (P≤0.05), and as chamber temperature increased this ratio decreased in the old (P≤0.030) but not in the young animals. This finding suggests that heat stress in an older organism requires a greater total cutaneous blood flow response in order to maintain sufficient flow in the subepidermal plexus for heat liberation.

Keywords

Heat Stress Chamber Temperature Circulatory Response Vascular Plexus Heat Liberation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

References

  1. 1.
    Burton, A.C.: Special features of the circulation of the skin, in Advanced Biology of Skin, Vol. 1, 1961, ppGoogle Scholar
  2. 2.
    Shock, N.W.: Systems integration, in The Biology of Aging, edited by Finch, C.E. and Hayflick, L., Van Nostrand, 1977, pp. 641–655.Google Scholar
  3. 3.
    Montaga, W., and Carlisle, K.: Structural changes in aging human skin. J. Invest. Derm., 73: 47–53, 1979.CrossRefGoogle Scholar
  4. 4.
    Ryan, T.J.: The microcirculation of the skin in old age. Geron. Clin., 8: 327–337, 1966.CrossRefGoogle Scholar
  5. 5.
    Popoff, N.W.: The digital vascular system. Arch. Path., 18: 295–330, 1934.Google Scholar
  6. 6.
    Allwood, M.J.: Blood flow in the foot and calf in the elderly: A comparison with that in young adults. Clin. Sci., 17: 331–338, 1958.PubMedGoogle Scholar
  7. 7.
    Richardson, D.R.: Effects of age on the response of the cutaneous circulation in the forearm to local heating. J. Geront. Med. Sci., 44: MI89–MI-94, 1989.Google Scholar
  8. 8.
    Sagawa, S., Shiraki, K., Yousef, M.K., and Miki, K.: Sweating and cardiovascular responses of aged men to heat exposure. J. Geront. Med. Sci., 43: M1–M8, 1988.Google Scholar
  9. 9.
    Shiracki, K., Sagawa, S., Yousef, M.K., Konda, N., and Miki, K.: Physiological responses of aged men to head-up tilt during heat exposure. J. Appl. Physiol., 63: 576–581, 1987.Google Scholar
  10. 10.
    Tan, O.T., and Stafford, T.J.: Cutaneous circulation, in Dermatology in General Medicine, edited by Fitzpatrick, T.B., Eisen, A.Z., Wolff, K., Freedberg, I.M., and Austen, K.F., 3rd edition, New York, McGraw-Hill, 1987, pp. 357–367.Google Scholar
  11. 11.
    Coffman, J.D.: Total and nutritional blood flow in the finger. Clin. Sci., 42: 243–250, 1972.PubMedGoogle Scholar
  12. 12.
    Richardson, D.R.: Relationship between digital artery and nailfold capillary flow velocities in human skin. Microcirculation, 2: 283–289, 1982.Google Scholar
  13. 13.
    Richardson, D.R., Schmitz, M., and Borchers, N.: Relative effects of static muscle contraction on digital artery and nailfold capillary blood flow velocities. Microvas. Res., 31: 157–169, 1986.CrossRefGoogle Scholar
  14. 14.
    Richardson, D.: Effects of gravity on regional and capillary blood flows in the human toe. Microvasc. Res., 35: 334–340, 1988.PubMedCrossRefGoogle Scholar
  15. 15.
    Richardson, D.R., and Shepherd, S.: The cutaneous microcirculation of the forearm in young and old subjects. Microvasc. Res., 41: 84–91, 1991.PubMedCrossRefGoogle Scholar
  16. 16.
    Brown, G.E., and Roth, G.M.: Biomicroscopy of the surface capillaries in normal and pathologic subjects. Med. J. Australia, 1: 499–506, 1927.Google Scholar
  17. 17.
    Richardson, D.R.: Orthostatic responses of regional and capillary blood flows in the toe circulation of different age groups of men. AGE, 11: 142–149, 1988.Google Scholar
  18. 18.
    Richardson, D.R., and Schwartz, R.: Comparison of capillary blood flow in the nailfold circulations of young and elderly men. AGE, 8: 70–75, 1985.CrossRefGoogle Scholar
  19. 19.
    Bos, G.M.J., Slaff, D.W., Majoor, G.D., Tangelder, G.J., and Reneman, R.S.: A model for chronic study of vascular morphology and reactivity of physically intact rat skin microcirculation. Int. J. Microcirc.: Clin. Exp., 6: 371–380, 1987.Google Scholar
  20. 20.
    Richardson, D.R., Shepherd, S., and McSorley, T.: Evaluation of the role of skin temperature in the response of cutaneous capillary blood flow to indirect heat. Microcirc. Endothelium and Lymphat., 4: 447–467, 1988.Google Scholar
  21. 21.
    Gemmell, R.T., and Hales, J.R.S.: Cutaneous arteriovenous anastomosis present in the tail but absent from the ear of the rat. J. Anat., 124: 355–358, 1977.PubMedGoogle Scholar
  22. 22.
    O’Leary, D.D., Johnson, J.M., and Taylor, W.F.: Mode of neural control mediating rat tail vasodilation during heating. J. Appl. Physiol., 59: 1533–1438, 1985.PubMedGoogle Scholar
  23. 23.
    Sparks, H.V.: Skin and muscle, in Peripheral Circulation, edited by Johnson, P.C., John Wiley and Sons, pp. 139–230, 1978.Google Scholar
  24. 24.
    Richardson, D.R., and Westphal, K.: Effects of local and total body heating on micro and macrocirculatory blood flow in the rat tail, in Microcirculation: An Update, edited by Tsuchiya, M., Amsterdam, Elsevier, 1987. pp. 509–510.Google Scholar
  25. 25.
    Aukland, K., and Wiig, H.: Hemodynamics and interstitial fluid pressure in the rat tail. Am. J. Physiol., 247: H80–H87, 1984.PubMedGoogle Scholar
  26. 26.
    Hoffman, H.J.: Survival for selected laboratory rat strains and stocks, in Development of the Rodent as a Model System of Aging, edited by Gibson, D.C., Adelman, R.C., and Finch, C., DHEW Pub. (NIH 79-161) Book II, U.S. Gov. Print. Off., 1978, 00. 19–34.Google Scholar
  27. 27.
    Hertzman, A.B.: Effects of heat on the cutaneous blood flow. Adv. Biol. of Skin, 2: 89–116, 1961.Google Scholar
  28. 28.
    Richardson, D., and Schwartz, R.: Comparison of resting capillary flow dynamics in the finger and the toe nailfolds. Microcirc. Endoth. Lymphat., 1: 645–656, 1984.Google Scholar
  29. 29.
    Cochran, W.G., and Cox, G.M.: Experimental Designs, 2nd Edition, New York, Wiley, 1957, pp.Google Scholar

Copyright information

© American Aging Association, Inc. 1992

Authors and Affiliations

  • Kathleen A. Westphal
    • 1
  • Daniel R. Richardson
    • 1
  1. 1.Department of Physiology and Biophysics, Sanders-Brown Research Center on AgingUniversity of Kentucky Medical CenterLexington

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