Advertisement

Pflügers Archiv

, Volume 395, Issue 2, pp 93–98 | Cite as

The role of adrenergic mechanisms in thermoregulatory control of blood flow through capillaries and arteriovenous anastomoses in the sheep hind limb

  • J. R. S. Hales
  • A. Foldes
  • A. A. Fawcett
  • R. B. King
Heart, Circulation, Respiration and Blood; Environmental and Exercise Physiology

Abstract

The possible role of adrenergic mechanisms in thermoregulatory changes in the partition of femoral blood flow between nutrient (capillary) and non-nutrient (arteriovenous anastomoses, AVA) circuits in the hind limb of conscious sheep has been investigated employing radioactive microsphere and electromagnetic blood flow measurement techniques. Constriction of AVAs, normally induced by spinal cooling, could be inhibited by phentolamine, whereas dilatation of AVAs, noramally induced by spinal heating, could be inhibited by noradrenaline or methoxamine. AVA constriction could be induced by noradrenaline or methoxamine, or dialation by phentolamine. Isoprenaline had a small dilator and propranolol a small constrictor effect on AVAs. It is concluded that adrenergic pathways involving predominantly α-receptors play a role in thermoregulatory changes in skin blood flow (through AVAs) elicited by manipulation of CNS temperature; under these conditions, β-receptors do not play any role, although manipulation of their activity will influence AVAs under non-thermoregulatory conditions. Capillary blood flows in skin, bone and fat were sensitive, at different ambient temperatures and to varying degrees, to some α-and β-adrenergic agents.

Key words

Thermoregulation Microspheres Arteriovenous anastomoses Adrenoceptor agonists/antagonists Blood flow partition Skin Bone 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Alexander G (1979) Cold thermogenesis. In: Robertshaw D (ed) Environmental physiology III. International review of physiology, vol 20. University Park Press, Baltimore, pp 43–155Google Scholar
  2. Foldes A, Hales JRS (1981) Adrenergic involvement in thermal control of capillaries and arteriovenous anastomoses in skin. In: Garlick D (ed) Progress in microcirculation research. CPME University of NSW, Sydney, pp 329–336Google Scholar
  3. Hales JRS (1974) Physiological responses to heat. In: Robertshaw D (ed) MTP international review of science, physiology. Series 1, pp 107–162Google Scholar
  4. Hales JRS (1980) Paradoxical effects of temperature of skin arteriovenous anastmoses. In: Szelényi Z, Székely M (eds) Contributions to thermal physiology. Akadémiai Kiadó, Budapest, pp 383–385Google Scholar
  5. Hales JRS (1982) Thermoregulatory requirements for regional circulatory adjustments to promote heat loss in animals. J Thermal Biol (in press)Google Scholar
  6. Hales JRS, Cliff WJ (1977) Direct observations on the behaviour of microspheres in microvasculature. Bibl Anat 15:87–91Google Scholar
  7. Hales JRS, Iriki M (1975) Integrated changes in regional circulatory activity evoked by spinal cord and peripheral thermoreceptor stimulation. Brain Res 81:267–279Google Scholar
  8. Hales JRS, Johnson KG (1981) Relationship between vascular and sweating responses to drugs in isolated skin. J Physiol 313:19PGoogle Scholar
  9. Hales JRS, Fawcett AA, Bennett JW (1978a) Radioactive microsphere measurement of the partition of bloodflow between capillaries and arteriovenous anastomoses in skin of sheep. Pflügers Arch 376:87–91Google Scholar
  10. Hales JRS, Fawcett AA, Bennett JW, Needham AD (1978b) Thermal control of bloodflow through capillaries and arteriovenous anastomoses in skin of sheep. Pflügers Arch 378:55–63Google Scholar
  11. Hales JRS, Iriki M, Tsuchiya K, Kozawa E (1978c) Thermally induced cutaneous sympathetic activity related to bloodflow through capillaries and arteriovenous anastomoses. Pflügers Arch 375:17–24Google Scholar
  12. Johansen K, Millard RW (1974) Cold induced neurogenic vasodilatation in skin of the giant fulmar,Macronectes giganteus. Am J Physiol 227:1232–1235Google Scholar
  13. Krönert H, Wurster RD, Pierau FR-K, Pleschka K (1980) Vasodilatory responses of arteriovenous anastomoses to local cold stimuli in the dog's tongue. Pflügers Arch 388:17–19Google Scholar
  14. Lunde PKM, Michelsen K (1970) Determination of cortical blood flow in rabbit femur by radioactive microspheres. Acta Physiol Scand 80:39–44Google Scholar
  15. McGregor DD (1979) Non-cholinergic vasodilator innervation in the feet of ducks and chickens. Am J Physiol 237:H112-H117Google Scholar
  16. Midtgard U, Bech C (1981) Responses to catecholamines and nerve stimulation of the perfusedrete tibiotarsale and associated blood vessels in the hind limb of the Mallard. Acta Physiol Scand 112:77–81Google Scholar
  17. Millard RW, Reite OB (1975) Peripheral vascular response to norepinephrine at temperatures from 2 to 4°C. J Appl Physiol 38:26–29Google Scholar
  18. Milnor WR (1968) In: Mountcastle VB (ed) Medical physiology. Mosby, St Louis, p 236Google Scholar
  19. Molyneux GS (1977) The role of arteriovenous anastomoses in the peripheral circulation. Proceedings of the Royal Society of Queensland 88:5–14Google Scholar
  20. Molyneux GS, Hales JRS (1979) Histological evidence for the involvement of noradrenergic transmission in control of cutaneous arteriovenous anastomoses. Proc Aust Physiol Pharmacol Soc 80:63Google Scholar
  21. Molyneux GS, Hales JRS (1982) The use of ultrastructural and histochemical techniques to correlate sympathetic activity with blood flow through cutaneous arteriovenous anastomoses in conscious sheep. Microcirc Clin Exp 1:41–53Google Scholar
  22. Murrish DE, Guard CL (1977) Cardiovascular adaptations of the giant petrel,Macronectes giganteus, to the Antarctic environment. In: Llano GA (ed) Adaptations within Antarctic ecosystems. Smithsonian Institute, Washington, p 551Google Scholar
  23. Oddy VH, Brown BW, Jones AW (1981) Measurement of organ blood flow using tritiated water. I. Hindlimb muscle blood flow in conscious ewes. Aust J Biol Sci 34:419–425Google Scholar
  24. Piiper J, Schurmeyer E (1955) Über den Einfluß von Doryl und Histamin auf die arteriovenösen Anastomosen in der Hundeextremität. Pflügers Arch 261:234–242Google Scholar
  25. Rowell LB (1977) Reflex control of cutaneous vasculature. J Invest Dermatol 69:154–166Google Scholar
  26. Schoutens A, Bergmann P, Verhas M (1979) Bone blood flow measured by85Sr microspheres and bone seeker clearances in the rat. Am J Physiol 236:H1–6Google Scholar
  27. Schönung W, Wagner H, Simon E (1972) Neurogenic vasodilatory component in the thermoregulatory skin blood flow response of the dog. Naunyn-Schmiedeberg's Arch Pharmacol 273:230–241Google Scholar
  28. Spence RJ, Rhodes BA, Wagner HW Jr (1972) Regulation of arteriovenous anastomotic and capillary blood flow in the dog leg. Am J Physiol 222:326–332Google Scholar
  29. Taylor SH, Sutherland GR, MacKenzie GJ, Staunton HP, Donald KW (1965) The circulatory effects of phenolamine in man with particular respect to changes in forearm blood flow. Clin Sci 28:265–284Google Scholar
  30. Thomson EM, Pleschka K (1980) Vasodilatory mechanisms in the tongue and nose of the dog under heat load. Pflügers Arch 387:161–166Google Scholar
  31. Vanhoutte PM, Leusen I (1978) Mechanisms of vasodilatation. Raven, New YorkGoogle Scholar
  32. Walther O, Iriki M, Simon E (1970) Cutaneous and visceral sympathetic activity during spinal cord heating and cooling in anaesthetized rabbits and cats. Pflügers Arch 319:162–184Google Scholar

Copyright information

© Springer-Verlag 1982

Authors and Affiliations

  • J. R. S. Hales
    • 1
  • A. Foldes
    • 1
  • A. A. Fawcett
    • 1
  • R. B. King
    • 1
  1. 1.Divison of Animal ProductionCSIROBlacktownAustralia

Personalised recommendations