An in vivo¹⁹F NMR study of isoflurane elimination as a function of age in rat brain

Abstract

In vivo 19F 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 t1/2 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 +/- 0.09 s) animals. For dipalmitoylphosphatidylcholine vesicles the monoexponential recovery also suggests rapidly exchanging averaged homogeneous lipid environments for the anesthetic, but the longer T1s (2.75 +/- 0.25 s) imply less restricted mobility compared with brain. Single T2 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 B1 inhomogeneity. The age-attenuated elimination kinetics for isoflurane are consistent with poorer cardiopulmonary function, whereas the T1 data suggest similar environments for the anesthetic in young and old brain tissue.

Comparing the effects of isoflurane and pentobarbital on the responses of cutaneous mechanoreceptive afferents

“…We chose that duration to be 30 minutes. According to published data [20], approximately 52-72% of arterial isoflurane has been eliminated at this point in time in rats after an average of 4 hours of exposure to 1.8% isoflurane. In the current study, animals had been under anesthesia for an average of 2.5 hours by the end of the first experimental block, so the above estimate of residual isoflurane is likely an overestimate.…”

Detection of the non‐steroidal anti‐inflammatory drug niflumic acid in humans: a combined 19F‐MRS in vivo and in vitro study

“…The value of in vivo 19 F-MRS has already been demonstrated in studies of various drugs including neuroleptics, 1-5 anaesthetics, 12,13 xenobiotics, and in particular the antimetabolite 5-fluorouracil (5-FU). [6][7][8][9][10][11] However, no in vivo data concerning the absorption and biotransformation of non-steroidal drugs in the human liver have been published so far.…”

“…A wide spectrum of fluorinated drugs like neuroleptics, [1][2][3][4][5] anticancer drugs like 5-fluoruracil, [6][7][8][9][10][11] anaesthetics 12,13 and other xenobiotics [14][15][16] have been investigated by in vivo 19 F-spectroscopy. For no known reason the group of non-steroidal anti-inflammatory drugs (NSAID) has been excluded so far and therefore in vivo data concerning the pharmacokinetics of this group are not available.…”

Balloon angioplasty of recoarctation of the neoaortic arch after the norwood operation: Factors affecting outcome and recurrence

“…Swiss Webster mice ( n = 5) were anesthetized with 1–2% isoflurane mixed with room air or O 2 followed by intravenous injection of CE NP (5 mL/kg) via the tail vein. The 19 F signal from isoflurane was barely detectable by MRI in contrast to the strong 19 F single emanating from CE NP in the blood stream, which is likely due to low blood/tissue retention and the short T of isoflurane (27). 1 H gradient‐echo cine images were acquired initially to position the slices to cover both LV and right ventricle (RV).…”