Concentration measures of volatile anesthetics in the aqueous phase using calcium sensitive electrodes.
J Neurosci Methods
; 81(1-2): 177-84, 1998 Jun 01.
Article
de En
| MEDLINE
| ID: mdl-9696323
ABSTRACT
Volatile anesthetic concentrations have been difficult to measure, but are an important experimental parameter for in vitro studies of anesthetic actions. Calcium sensitive electrodes were investigated as a means of continuously monitoring anesthetic concentrations in artificial cerebrospinal fluids (ACSF). Anesthetic-induced Ca2+ electrode signals were compared at room (22 degrees C) and physiological (35 degrees C) temperatures. Electrophysiological measures of anesthetic effects on synaptic potentials provided a bioassay. Halothane and isoflurane produced negative changes in calcium electrode potentials which were linearly related to concentrations over a clinically useful range (0.5-1.5 MAC). Anesthetic-induced voltages persisted in nominally zero Ca2+ ACSF and even in deionized water. A good correlation (r>0.9) was found for calcium electrode measures of anesthetic concentration and synaptic response depression produced by halothane, at both 22 and 35 degrees C. These results support three conclusions:
(1) calcium sensitive electrodes provide a useful measure of volatile anesthetic concentrations in aqueous solution. (2) Care must be taken when using these electrodes for Ca2+ concentration measurements, if a volatile anesthetic is also to be used, since the anesthetic could introduce an appreciable error (>50%). (3) A temperature change of 13 degrees C had surprisingly little effect on Ca2+ electrode responses or on synaptic depression produced by anesthetics.
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Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Calcium
/
Électrodes sélectives
/
Anesthésiques par inhalation
Type d'étude:
Diagnostic_studies
Limites:
Animals
Langue:
En
Journal:
J Neurosci Methods
Année:
1998
Type de document:
Article
Pays d'affiliation:
États-Unis d'Amérique