Significance of endogenous opioids in the maintenance of cerebral and spinal vascular CO2-sensitivity in deep hemorrhagic hypotension

Peter Sandor, Martin Reivich, K. Komjáti

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

High CO2-sensitivity, one of the major characteristics of the cerebrovascular bed, has been shown to be influenced by a variety of factors. There are no reports, however, on the involvement of the endogenous opioid peptides in the modulation of the CO2-sensitivity of the cerebral and spinal cord vessels, either in normotensive or, in hypotensive conditions. The effect of general opiate receptor blockade (1.0mg/kg naloxone, i.v.) on regional cerebrovascular CO2-sensitivity was studied with radiolabeled microspheres in 10 distinct brain and spinal cord regions of the anesthetized cat. The CO2-induced flow changes were investigated in normotensive, in moderately hypotensive (MAP=80mmHg) and in deep hypotensive cats (MAP=40mmHg). The systemic arterial pressure was lowered by hemorrhage. In the normotensive cats, opiate receptor blockade caused no changes in the vascular CO2-sensitivity in the investigated cerebral and spinal cord regions. In moderate hypotension, cerebral and spinal CO2-sensitivity was significantly reduced by the hemorrhage itself, but remained unaffected by the naloxone administration. In deep hemorrhagic hypotension, however, general opiate receptor blockade resulted not only in a further reduction of the already impaired CO2-sensitivity, but even in a reversal of the effect of CO2 from flow increase to flow decrease. These results indicate that endogenous opioid peptides, which do not seem to influence cerebrovascular reactions in steady-state, normotensive conditions, may contribute significantly to the maintenance of the normal vasodilatory response of the cerebral and spinal cord vessels to CO2 during hemorrhage-induced deep arterial hypotension.

Original languageEnglish
Pages (from-to)433-438
Number of pages6
JournalBrain Research Bulletin
Volume59
Issue number6
DOIs
Publication statusPublished - Feb 15 2003

Fingerprint

Hypotension
Opioid Analgesics
Blood Vessels
Spinal Cord
Opioid Receptors
Maintenance
Cats
Opioid Peptides
Hemorrhage
Naloxone
Microspheres
Arterial Pressure
Brain

Keywords

  • Cerebral and spinal blood flow
  • CO-responsiveness
  • Endogenous opiates
  • Hemorrhage
  • Naloxone

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Significance of endogenous opioids in the maintenance of cerebral and spinal vascular CO2-sensitivity in deep hemorrhagic hypotension. / Sandor, Peter; Reivich, Martin; Komjáti, K.

In: Brain Research Bulletin, Vol. 59, No. 6, 15.02.2003, p. 433-438.

Research output: Contribution to journalArticle

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