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An in vivo 19 F NMR study of isoflurane elimination as a function of age in rat brain
Author(s) -
Chen M.,
Olsen J. I.,
Stolk J. A.,
Schweizer M. P.,
Sha M.,
Ueda I.
Publication year - 1992
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1940050304
Subject(s) - isoflurane , in vivo , anesthetic , chemistry , kinetics , anesthesia , nuclear magnetic resonance , biology , medicine , physics , quantum mechanics , microbiology and biotechnology , organic chemistry
In vivo 19 F NMR at 4.7 T has shown that the biphasic elimination of the vapor anesthetic isoflurane from rat brain is ca 15% slower in old (23‐24 months) animals compared with young (5–6 months) animals. The fast kinetic component has a t 1/2 of ca 7–9 min and the slow event, 100–115 min. Gas chromatographic measurement of arterial blood elimination displays age attenuation to the same extent, although a monophasic kinetic process (6–7 min). The slow wash‐out from brain is thought to involve elimination from intracranial fatty tissue as postulated by others in rabbit brain. Longitudinal relaxation time measurements show monoexponential recovery and essentially identical values for young (1.09+0.11 s) and old (1.04±0.09s) animals. For dipalmitoylphosphatidylcholine vesicles the monoexponential recovery also suggests rapidly exchanging averaged homogeneous lipid environments for the anesthetic, but the longer T 1 s (2.75±0.25 s) imply less restricted mobility compared with brain. Single T 2 values were obtained in vivo , indicating either a single compartment or rapid exchange between multiple environments. These measurements were inconsistent, undoubtedly as a result of B 1 inhomogeneity. The age‐attenuated elimination kinetics for isoflurane are consistent with poorer cardiopulmonary function, whereas the T 1 data suggest similar environments for the anesthetic in young and old brain tissue.