In:
Journal of Neurosurgery, Journal of Neurosurgery Publishing Group (JNSPG), Vol. 97, No. 1 ( 2002-07), p. 97-103
Kurzfassung:
Object. Disruption of ionic homeostasis during ischemia is a well-characterized event and is identified by a rise in the concentration of extracellular potassium [K + ] e , with a concomitant reduction in the concentration of extracellular sodium [Na + ] e . Results of clinical studies in which microdialysis has been used, however, have shown only modest changes in the levels of extracellular ions. The object of this study was to measure [K + ] e and [Na + ] e by using ion-selective electrodes (ISEs) and to compare these measurements with those obtained using the well-established method of microdialysis. Methods. Fifteen Sprague—Dawley rats were separated into three groups. Five animals were subjected to a 15-minute period of ischemia, and another five animals to a 60-minute period of ischemia; animals in both of these groups received K + -free microdialysis perfusate. The third group of five rats underwent a 60-minute period of ischemia and received a reduced-Na + microdialysis perfusate. Transient forebrain ischemia was produced by bilateral carotid artery occlusion combined with hypotension. A custom-fabricated glass Na + electrode and a flexible plastic K + and reference electrodes were used to monitor extracellular ion transients. Microdialysis samples were obtained with the aid of a 2-mm microdialysis probe that was perfused with K + -free mock cerebrospinal fluid at a rate of 2 µl/minute. Baseline measurements of [K + ] e and [Na + ] e , obtained using ISEs, were 3.41 ± 0.09 mM and 145 ± 7.75 mM, respectively. Ischemia resulted in a rapid accumulation of [K + ] e (in animals subjected to 15 minutes of ischemia, the concentration was 41.9 ± 13.7 mM; and in animals subjected to 60 minutes of ischemia, the concentration was 66.9 ± 11.5 mM), with a concomitant decrease in [Na + ] e (in animals subjected to 15 minutes of ischemia, the concentration was 71.7 ± 2.9 mM; and in animals subjected to 60 minutes of ischemia, the concentration was 74.7 ± 1.9 mM). A comparison of microdialysis and ISE methods revealed that microdialysis underestimated the [K + ] e changes and was insensitive to concomitant [Na + ] e alterations that occur during ischemia. Conclusions. Our results indicate that the flexible ISE is a reliable and accurate tool for monitoring ionic dysfunction that accompanies brain injury.
Materialart:
Online-Ressource
ISSN:
0022-3085
DOI:
10.3171/jns.2002.97.1.0097
Sprache:
Unbekannt
Verlag:
Journal of Neurosurgery Publishing Group (JNSPG)
Publikationsdatum:
2002
ZDB Id:
2026156-1
