Effects of the Anesthetic Dibucaine on the31P NMR Spectra of Maize Root Tissue

Abstract

We present the first in vivo31P NMR study describing the effect of the anesthetic dibucaine on the levels of phosphorus-containing metabolites (G-6-P, Pi, 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 Ca2+concentration at several pH values. Our results indicate that dibucaine alters the31P spectra and the membrane-lipid composition of the roots upon introduction into the perfusate medium. Ca2+inhibits the effects of the dibucaine as monitored by suppression of the31P 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 Ca2+), 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 the31P NMR spectral studies.