We present the first <i>in vivo</i> <sup>31</sup>P NMR study describing the effect of the anesthetic dibucaine on the levels of phosphorus-containing metabolites (G-6-P, P<sub>i</sub>, NTP, NADP, and UDPG) in maize root tissue which was maintained in an aerobic state through modern perfusion techniques. The effects of dibucaine are demonstrated as a function of Ca<sup>2+</sup> concentration at several pH values. Our results indicate that dibucaine alters the <sup>31</sup>P spectra and the membrane-lipid composition of the roots upon introduction into the perfusate medium. Ca<sup>2+</sup> inhibits the effects of the dibucaine as monitored by suppression of the <sup>31</sup>P spectral changes induced by the anesthetic alone. Desaturase enzymatic inhibition has also been shown to occur in the presence of the anesthetic (in the absence of Ca<sup>2+</sup>), resulting in increased relative saturation of the fatty acids comprising the root tissue, with a marked decrease in linoleate (18:2) balanced by proportional increases in the more saturated fatty acid species. These compositional changes have been evaluated with respect to the real-time metabolic results as observed throughout the <sup>31</sup>P NMR spectral studies.
W. V. Gerasimowicz, M. J. Kurantz, P. E. Pfeffer, and N. A. Psorsas, "Effects of the Anesthetic Dibucaine on the 31P NMR Spectra of Maize Root Tissue," Appl. Spectrosc. 43, 1032-1038 (1989)