Noninvasive Observations of Fluorinated Anesthetics in Rabbit Brain by Fluorine-19 Nuclear Magnetic Resonance

Abstract

Fluorinated anesthetics were observed noninvasively in the brain of intact rabbits with fluorine-19 nuclear magnetic resonance spectroscopy. High-resolution fluorine-19 spectra of halothane, methoxyflurane, and isoflurane were obtained with a surface coil centered over the calvarium. Elimination of halothane from the brain was also monitored by this technique. Residual fluorine-19 signals from halothane (or a metabolite) could be detected as long as 98 hours after termination of anesthesia. These observations demonstrate the feasibility of using this technique to study the fate of fluorinated anesthetics in live mammals.

Temporal accumulation and localization of isoflurane in the C57BL/6 mouse and assessment of its potential contamination in 19F MRI with perfluoro‐crown‐ether‐labeled cardiac progenitor cells at 9.4 Tesla

“…These peaks may interfere with the detection of fluorinated agents in vivo (chemical shift range of ‐126.6–9.1 ppm with respect to CFCl 3 and ‐50–86 ppm with respect to trifluoroacetic acid [TFA]) due to potential spectral overlaps. Furthermore, despite the existence of numerous prior 19 F MRI studies on the uptake and clearance characteristics of ISO in the brain in vivo, the localization of ISO in cardiac thoracic and peripheral skeletal tissues, its bio‐distribution, accumulation, kinetics, and possible interference with 19 F labels has not been investigated in detail. Additionally, only a few reported cardiovascular applications of fluorinated agents exist, and investigations into the possible implications of the use of ISO have been speculative …”

Biochemistry of the Elemental Halogens and Inorganic Halides

“…The relatively narrow linewidths observed in this study suggested that the anesthetics possessed a fair amount of mobility in the rabbit brain. The time course of clearance of halothane from the rabbit brain, followed by 19F-NMR spectroscopy, was significantly longer than anticipated (Wyrwicz et at., 1983). In subsequent studies, enflurane and halothane were found to reside in two compartments in the rabbit brain, characterized by different time constants for clearance of the anesthetics.…”

NMR studies of drug metabolism and disposition

“…. f h 19 resonance imagmg 0 t e F nucleus has been used for mapping the disposition of fluorinated drugs (14)(15)(16).…”