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Naloxone does not inhibit the attenuation of the response to severe haemorrhage seen after simulated injury in the anaesthetized rat.

Sawdon, Marina, Ohnishi, Mitsuo, Little, Rodney A and Kirkman, Emrys (2009) Naloxone does not inhibit the attenuation of the response to severe haemorrhage seen after simulated injury in the anaesthetized rat. Experimental physiology, 94 (6). pp. 641-7. ISSN 1469-445X

Item Type: Article

Abstract

Severe haemorrhage leads to a reflex bradycardia and hypotension. This is thought to be protective, but is attenuated by both concomitant musculoskeletal injury and exogenous morphine. The aim of this study was to determine whether the injury-induced attenuation of the response to severe haemorrhage could be blocked by naloxone. Male Wistar rats, terminally anaesthetized with alphadolone/alphaxalone (19-20 mg kg(-1) h(-1)I.V.), were randomly allocated to one of four groups. In groups I and IV, haemorrhage was simple [40% of estimated total blood volume (BV)], while in groups II and III it was initiated 10 min after the onset of bilateral hindlimb ischaemia (a model of musculoskeletal injury). Groups I and II received 20 microl of 0.9% saline intracerebroventricularly (I.C.V.) immediately before haemorrhage, while groups III and IV received 20 microg of naloxone I.C.V., in the same volume. In group I, the bradycardia reached its peak after the loss of 32.8 +/- 0.3% BV (mean +/- S.E.M.). Blood pressure did not fall significantly until the loss of 15.0 +/- 3.0% BV. The response in group IV was not significantly different from group I. By contrast, the bradycardia was absent after similar blood losses in groups II and III, while hypotension was attenuated. These results indicate that naloxone, at a dose known to be effective in blocking mu-opioid receptors and preventing other aspects of the response to injury, does not prevent the injury-induced attenuation of the response to severe haemorrhage. Thus the attenuation of the response to blood loss by injury is unlikely to be mediated via the mu-opioid receptors.

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More Information

Depositing User: Marina Sawdon

Identifiers

Item ID: 8118
ISSN: 1469-445X
URI: http://sure.sunderland.ac.uk/id/eprint/8118
Official URL: https://doi.org/10.1113/expphysiol.2008.045757

Users with ORCIDS

ORCID for Marina Sawdon: ORCID iD orcid.org/0000-0002-8668-257X

Catalogue record

Date Deposited: 13 Oct 2017 15:09
Last Modified: 18 Dec 2019 15:41

Contributors

Author: Marina Sawdon ORCID iD
Author: Mitsuo Ohnishi
Author: Rodney A Little
Author: Emrys Kirkman

University Divisions

Faculty of Health Sciences and Wellbeing
Faculty of Health Sciences and Wellbeing > School of Medicine

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