Impact of Hypo- and Hyper-capnia on Spreading Depolarizations in Rat Cerebral Cortex.

Autor: Shukla G; University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA., Parks K; Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA., Smith DW; Delta Chase, LLC, West Chester, OH 45069, USA., Hartings JA; Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA. Electronic address: jed.hartings@uc.edu.
Jazyk: angličtina
Zdroj: Neuroscience [Neuroscience] 2023 Oct 15; Vol. 530, pp. 46-55. Date of Electronic Publication: 2023 Aug 26.
DOI: 10.1016/j.neuroscience.2023.08.029
Abstrakt: Patients with traumatic brain injury are typically maintained at low-normal levels of arterial partial pressure of carbon dioxide (P a CO 2 ) to counteract the risk of elevated intracranial pressure during intensive care. However, several studies suggest that management at hypercarbic levels may have therapeutic benefit. Here we examined the impact of CO 2 levels on spreading depolarizations (SD), a mechanism and marker of acute lesion development in stroke and brain trauma. In an acute preparation of mechanically ventilated (30/70 O 2 /N 2 ) female rats, SDs were evoked by cortical KCl application and monitored by electrophysiology and laser doppler flowmetry; CO 2 levels were adjusted by ventilator settings and supplemental CO 2 . During 90 min of KCl application, rats were maintained at hypocapnia (end-tidal CO 2 22 ± 2 mmHg) or hypercapnia (57 ± 4 mmHg) but did not differ significantly in arterial pH (7.31 ± 0.10 vs. 7.22 ± 0.08, p = 0.31) or other variables. Surprisingly, there was no difference between groups in the number of SDs recorded (10.7 ± 4.2 vs. 11.7 ± 3.1; n = 3 rats/group; p = 0.75) nor in SD durations (64 ± 27 vs. 69 ± 37 sec, p = 0.54). In separate experiments (n = 3), hypoxia was induced by decreasing inhaled O 2 to 10% and single SDs were induced under interleaved conditions of hypo-, normo-, and hypercapnia. No differences in SD duration were observed. In both normoxia and hypoxia experiments, however, mean arterial pressures were negatively correlated with SD durations (normoxia R 2  = -0.29; hypoxia R 2  = -0.61, p's < 0.001). Our results suggest that any therapeutic benefit of elevated CO 2 therapy may be dependent on an acidic shift in pH or may only be observed in conditions of focal brain injury.
(Copyright © 2023 IBRO. Published by Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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