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Norepinephrine-induced hyperglycemia does not increase cortical lactate in brain-injured rats.


Stover, J F; Sakowitz, O W; Thomale, U W; Kroppenstedt, S N; Unterberg, A W (2002). Norepinephrine-induced hyperglycemia does not increase cortical lactate in brain-injured rats. Intensive Care Medicine, 28(10):1491-1497.

Abstract

OBJECTIVE: Hyperglycemia aggravates ischemic brain damage. Since catecholamines increase hepatic gluconeogenesis, resulting in hyperglycemia, we investigated whether norepinephrine and dopamine elevate arterial blood glucose, thereby increasing pericontusional cortical glucose and lactate concentrations and brain edema in brain-injured rats. DESIGN: Prospective, randomized, controlled animal study. SUBJECTS: Male Sprague Dawley rats. INTERVENTIONS: Physiological saline solution, norepinephrine, or dopamine were infused intravenously for 90 min beginning 4.5 h after inducing a focal cortical contusion. Blood glucose, lactate, and pericontusional cortical extracellular glucose and lactate were determined before, during and up to 60 min after the infusion period. Thereafter brains were removed to assess hemispheric water content. MEASUREMENTS AND RESULTS: Continuous norepinephrine and dopamine infusion significantly increased pericontusional glucose concentrations, being mostly sustained by norepinephrine (NaCl: 1.3+/-0.2, dopamine: 2.7+/-0.2, norepinephrine: 4.8+/-1.1 mM). While arterial blood glucose was only significantly elevated in norepinephrine-treated rats from 8.6+/-0.6 to 12.6+/-1.6 mM, the extracellular to blood glucose ratio was significantly increased in dopamine- and norepinephrine-treated rats (0.28+/-0.01 and 0.38+/-0.05 vs. 0.17+/-0.01). Plasma and pericontusional lactate remained unchanged, and brain edema was similar in all groups. CONCLUSIONS: Norepinephrine and dopamine significantly increased pericontusional glucose concentrations which did not elevate extracellular lactate and aggravate underlying posttraumatic edema formation. In addition to possibly increased facilitated endothelial glucose transport, the elevated extracellular to blood glucose ratio suggests a passive concentration- and pressure- dependent entry via a damaged blood-brain barrier. This might contribute to the observed reversible increase in extracellular glucose.

OBJECTIVE: Hyperglycemia aggravates ischemic brain damage. Since catecholamines increase hepatic gluconeogenesis, resulting in hyperglycemia, we investigated whether norepinephrine and dopamine elevate arterial blood glucose, thereby increasing pericontusional cortical glucose and lactate concentrations and brain edema in brain-injured rats. DESIGN: Prospective, randomized, controlled animal study. SUBJECTS: Male Sprague Dawley rats. INTERVENTIONS: Physiological saline solution, norepinephrine, or dopamine were infused intravenously for 90 min beginning 4.5 h after inducing a focal cortical contusion. Blood glucose, lactate, and pericontusional cortical extracellular glucose and lactate were determined before, during and up to 60 min after the infusion period. Thereafter brains were removed to assess hemispheric water content. MEASUREMENTS AND RESULTS: Continuous norepinephrine and dopamine infusion significantly increased pericontusional glucose concentrations, being mostly sustained by norepinephrine (NaCl: 1.3+/-0.2, dopamine: 2.7+/-0.2, norepinephrine: 4.8+/-1.1 mM). While arterial blood glucose was only significantly elevated in norepinephrine-treated rats from 8.6+/-0.6 to 12.6+/-1.6 mM, the extracellular to blood glucose ratio was significantly increased in dopamine- and norepinephrine-treated rats (0.28+/-0.01 and 0.38+/-0.05 vs. 0.17+/-0.01). Plasma and pericontusional lactate remained unchanged, and brain edema was similar in all groups. CONCLUSIONS: Norepinephrine and dopamine significantly increased pericontusional glucose concentrations which did not elevate extracellular lactate and aggravate underlying posttraumatic edema formation. In addition to possibly increased facilitated endothelial glucose transport, the elevated extracellular to blood glucose ratio suggests a passive concentration- and pressure- dependent entry via a damaged blood-brain barrier. This might contribute to the observed reversible increase in extracellular glucose.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Division of Surgical Intensive Care Medicine
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2002
Deposited On:02 Oct 2009 05:29
Last Modified:05 Apr 2016 12:51
Publisher:Springer
ISSN:0342-4642
Additional Information:The original publication is available at www.springerlink.com
Publisher DOI:10.1007/s00134-002-1431-2
PubMed ID:12373476
Permanent URL: http://doi.org/10.5167/uzh-10650

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