Neural effects of systemic hypoxia and hypercapnia on hindlimb vascular resistance in acute spinal cats

  • Charles V. Rohlicek
  • Canio Polosa
Heart, Circulation, Respiration and Blood; Environmental and Exercise Physiology


The effects of systemic hypoxia and hypercapnia on the neurogenic component of hindlimb vascular resistance were studied in 10 unanesthetized acute Cl spinal cats. Hindlimb perfusion pressure (PP) was measured under conditions of constant flow of normoxic and normocapnic blood from a donor cat. Ventilation with 5% CO2 and 10% CO2 in P2 caused increases in PP of 15±2 (mean±SE) mm Hg and 27±3 mm Hg from a control level of 106±6 mm Hg during ventilation with 100% O2. Changing the inspired gas mixture from 95% O2 plus 5% CO2 to 12.5%, 10%, 7.5%, or 5% O2 plus 5% CO2 in N2 caused increases in PP of 1.5±1, 14±2, 38±6, and 69±15 mm Hg respectively from a control level of 121±9 mm Hg. These vasoconstrictor effects were abolished by ganglionic blockade with hexamethonium (10 mg/kg iv). We conclude that in the acute Cl spinal cat a large part of the population of sympathetic preganglionic neurons in the lumbar spinal cord, controlling vascular smooth muscle of the hindlimb, is excited by systemic hypoxia or hypercapnia over a considerable range ofPaO2 andPaCO2 values.

Key words

Autonomic nervous system Central chemosensitivity Peripheral blood flow Sympathetic tone Sympathetic excitation 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Alexander RS (1945) The effects of blood flow and anoxia on spinal cardiovascular centers. Am J Physiol 143:698–708Google Scholar
  2. Bower EA (1975) The influence of hypercapnia and hypoxia on the activity recorded from intestinal sympathetic nerves in the rabbit with cut sinus nerves. J Physiol 246:68P-69PGoogle Scholar
  3. Brown AM, Berman PR (1970) Mechanisms of excitation of aplysia neurons by carbon dioxide. J Gen Physiol 56:543–558PubMedCrossRefGoogle Scholar
  4. Chalazonitis N (1963) Effects of changes in\(Pa_{CO_2 }\) and\(P_{{\text{O}}_2 }\) on rhythmic potentials from giant neurons. Ann NY Acad Sci 109:451–479PubMedCrossRefGoogle Scholar
  5. Collewijn H, van Harreveld A (1966) Membrane potential of cerebral cortical cells during spreading depression and asphyxia. Exp Neurol 15:425–436PubMedCrossRefGoogle Scholar
  6. Downing SE, Siegel JH (1963) Baroreceptors and chemoreceptors influence on sympathetic discharge to the heart. Am J Physiol 204(3):471–479Google Scholar
  7. Goltzner F, Grusser OJ (1967) Cortical DC potential, EEG, and membrane potential during seizure activity and hypoxia. EEG Cl Neur 23:379–378Google Scholar
  8. Gregor M, Janig W (1977) Effects of systemic hypoxia and hypercapnia on cutaneous and muscle vasoconstrictor neurons to the cat's hindlimb. Pflügers Arch 36:71–81CrossRefGoogle Scholar
  9. Hanna BD, Lioy F, Polosa C (1979) The effect of cold blockade of the medullary chemoreceptors on the CO2 modulation of vascular tone and heart rate. Can J Physiol Pharmacol 57:461–468PubMedCrossRefGoogle Scholar
  10. Hanna BD, Lioy F, Polosa C (1981) Role of carotid and central chemoreceptors in the CO2 response of sympathetic preganglionic neurons. J Auton Nerv Syst 3:421–435PubMedCrossRefGoogle Scholar
  11. Hansen AJ, Homsgaard J, Jahnsen H (1982) Anoxia increases potassium conductance in hippocampal nerve cells. Acta Physiol Scand 115:301–310PubMedCrossRefGoogle Scholar
  12. Heymans C, Neil E (1958) Reflexogenic areas of the cardiovascular system. Churchill, LondonGoogle Scholar
  13. Howe A, Pack RJ, Wise JCR (1981) Arterial chemoreceptor-like activity in the abdominal vagus of the rat. J Physiol 320:309–318PubMedGoogle Scholar
  14. Iriki M, Kozawa E (1975) Factors controlling the regional differentiation of sympathetic outflow-influence of the chemoreceptor reflex. Brain Res 87:281–291PubMedCrossRefGoogle Scholar
  15. Janig W, Spilok N (1978) Functional organization of sympathetic innervation supplying hairless skin of the hindpaws in chronic spinal cats. Pflügers Arch 377:25–31PubMedCrossRefGoogle Scholar
  16. Kehrel H v, Mutharoglu N, Weidinger H (1961) Über phasische Einflüsse und den Einfluß der Asphyxie auf den Tonus des sympathischen Kreislaufzentrums. Z Kreislaufforsch 12:334–351Google Scholar
  17. Kolmodin GM, Skoglund CR (1959) Influence of asphyxia on membrane potential level and action potential of spinal motor and interneurons. Acta Physiol Scand 45:1–18PubMedCrossRefGoogle Scholar
  18. Korner PI (1959) Circulatory adaptations in hypoxia. Physiol Rev 39:687–730PubMedGoogle Scholar
  19. Krnjevic K, Randic M, Siesjo BK (1965) Cortical CO2 tension and neuronal excitability. J Physiol (Lond) 176:105–122Google Scholar
  20. Lioy F, Hanna BD, Polosa C (1981) Cardiovascular control by medullary surface chemoreceptors. J Auton Nerv Syst 3:1–7PubMedCrossRefGoogle Scholar
  21. Mannard A, Polosa C (1973) Analysis of background firing of single sympathetic preganglionic neurons of cat cervical nerve. J Neurophysiol 36:398–408PubMedGoogle Scholar
  22. Papajewski W, Klee MR, Wagner A (1969) The action of raised CO2 pressure on the excitability of spinal motoneurons. Electroencephalogr Clin Neurophysiol 17:618Google Scholar
  23. Polosa C (1968) Spontaneous activity of sympathetic preganglionic neurons. Clin J Physiol Pharmacol 46:887–896CrossRefGoogle Scholar
  24. Preiss G, Polosa C (1977) The relation between end-tidal CO2 and discharge patterns of sympathetic preganglionic neurons. Brain Res 122:255–267PubMedCrossRefGoogle Scholar
  25. Ritchie JM (1973) Energetic aspects of nerve conduction: the relationship between heat production, electrical activity and metabolism. Progr Biophys Molec 26:147–187CrossRefGoogle Scholar
  26. Rohlicek CV, Polosa C (1981) Hypoxic responses of sympathetic preganglionic neurons in the acute spinal cat. Am J Physiol 241:H679-H683PubMedGoogle Scholar
  27. Rohlicek CV, Polosa C (1983) Hypoxic responses of sympathetic preganglionic neurons in sino-aortic denervated cats. Am J Physiol 244:H681-H686PubMedGoogle Scholar
  28. Rohlicek CV, Hakim T, Polosa C (1984) Neural effects of systemic hypoxia on hindlimb vascular resistance in sino-aortic denervated cats. Pflügers Arch 401:380–384PubMedCrossRefGoogle Scholar
  29. Segal JR (1970) Metabolic dependence of resting action potential of frog nerve. Am J Physiol 219:1216–1225PubMedGoogle Scholar
  30. Siegel S (1956) Nonparametric statistics for the behavioural sciences. McGraw-Hill, New YorkGoogle Scholar
  31. Somlyo AP, Somlyo AV (1970) Vascular smooth muscle. Pharmacol Rev 22:249–253PubMedGoogle Scholar
  32. Suutarinen T (1966) Cardiovascular response to changes in arterial carbon dioxide tension. Acta Physiol Scand 67 (Suppl 266):1–76Google Scholar
  33. Szulczyk P, Trzebski A (1976) The local effect of pH changes in the cerebrospinal fluid on the ventrolateral medulla oblongata and on the spinal cord surface on the activity of cardiac and vertebral nerves. Acta Physiol Pol 27(1):9–17PubMedGoogle Scholar
  34. Trzebski A, Zielinski A, Majcherczyk S, Lipski J, Szulczyk P (1974) Effect of chemical stimulation and depression of the medullary superficial areas on the respiratory motoneurons discharges, sympathetic activity and efferent control of carotid area receptors. In: Umbach W, Koepchen HP (eds) Central-rhythmic and regulation. Stuttgart, Hyppokrates, pp 170–177Google Scholar
  35. Zhang TX, Rohlicek CV, Polosa C (1982) Responses of sympathetic preganglionic neurons to systemic hypercapnia in the acute spinal cat. J Auton Nerv Syst 6:381–389PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • Charles V. Rohlicek
    • 1
  • Canio Polosa
    • 1
  1. 1.Department of PhysiologyMcGill UniversityMontrealCanada

Personalised recommendations