Effect of halothane on the natural-abundance 13C NMR spectra of excised rat brain.

Halothane increases the intensity of the 30.5- and 129-ppm resonances in 13C nuclear magnetic resonance spectra of excised rat brain, of phospholipid vesicles prepared from chloroform-methanol extract of rat brain, and of brain excised from rats anesthetized with halothane. The 13C spin-lattice relaxation times of the 30.5- and 129-ppm resonances are increased in excised brain, or phospholipid vesicles, upon addition of halothane, and they are also increased in brain excised from rats anesthetized with halothane. Excised brain and its membrane-rich subcellular fractions interact with [14C]halothane reversibly. The interaction is virtually abolished when the phospholipids are extracted from the brain. The [14C]halothane content of the brain membranes is correlated with the halothane-induced increase in the integral of the 129-ppm resonance. From this correlation and from the phospholipid content of the membranes, a halothane concentration of 3.34 mM and a partition of 0.057 mol of halothane/mol of phospholipid may be calculated in the brain of anesthetized rats.